12 Best Freshwater Clam Supplies (October 2026)

Best freshwater clam supplies come down to five things: a soft sand bed the animal can bury into, clean mature water, a gentle current, enough suspended food in the column, and test gear to catch trouble before the clam closes up. I have kept filter-feeding bivalves in community tanks for years and this is the shortlist I hand to anyone who asks.

Before we get into products, the thing almost every pet store gets wrong: clams sold in freshwater tanks are usually Asian clams or golden clams, not the marine giant clams that dominate most search results. A freshwater clam is a filter feeder, not a decoration and not a filter replacement. It draws water in through one short siphon, traps microscopic particles on ciliated gills, and pushes water back out through a second siphon. That single fact drives every purchase on this list.

I built this roundup around what a clam physically needs rather than around brand names. Each pick below is tied to a specific job: buffering, seeding bacteria, gentle flow, monitoring, or transport. I also flag the honest limitation of every item, because the number one complaint in every forum thread I have read is that clams die slowly and silently and nobody knew why.

If you only read one section, read the checklist. It is the whole shopping list in twelve lines.

Our Top 3 Freshwater Clam Supplies Tested in 2026

These three cover the parts of clam keeping that quietly decide survival. Prime conditions the water, BioMax keeps ammonia down so the clam is not poisoned by its own tank, and the test strips tell you when something has shifted.

Comparing the Best Freshwater Clam Supplies in 2026

The Freshwater Clam Supplies Checklist

Twelve items, each one earning its place. If you buy nothing else, buy the first four.

• Soft fine sand substrate - a clam cannot bury without it, and it will not open and feed while sitting on bare glass or coarse gravel.
• Water conditioner - chlorine and chloramine burn gill tissue long before a clam shows any sign of stress.
• Biological filter media - clams are added to the bioload, so the biofilter has to be strong before they arrive.
• Gentle filtration - a sponge filter or a low-flow canister outlet, positioned so the current does not blast the siphons.
• Nitrate and alkalinity tests - stability matters more than hitting a perfect number, and you cannot track stability without measuring it.
• A pH buffer in the substrate - a calcium carbonate sand holds pH steady through the swings that kill clams.
• An air stone for surface agitation - gas exchange at the surface keeps the water column oxygenated for the animal and the bacteria.
• Live culture or filtered greens - only if your tank is clean enough that suspended food is scarce, and only as insurance.
• A transport container and drip line - a bag from the store is not an acclimation plan.
• A quarantine sponge filter - lets you hold a new clam separate while you confirm it is opening and feeding.
• A bright light or lamp with a PAR reading spot - clams evolved in high light zones and do poorly in a dim corner.
• A camera or frequent hands-on observation habit - predation and slow mortality are both invisible without it.

1. Seachem Prime - The Conditioner That Every Clam Setup Needs

This is the product I put in every clam setup before the animal goes in, and it is the one I recommend most often. Clams pump enormous volumes of water across their gills every hour, which means they are exposed to whatever is dissolved in that water far more intensively than a slow-swimming fish is. Any chlorine or chloramine left in the fill water attacks that gill tissue first.

What I like most is the safety margin. The label treats one capful for 50 gallons, and it is considered safe at five times that in an emergency, which matters when you are topping off a 40 gallon tank at midnight with a nervous clam already in the water. It also detoxifies ammonia, which is the other thing that quietly kills clams in a tank that has not finished cycling.

The honest limitation is the smell. Every bottle has it, and it is genuinely unpleasant for the first thirty seconds. Reviewers also note that locked toxins are released after a 24 to 48 hour window, so this is not a substitute for regular water changes. It also will not do anything for a clam that is already sitting in old, ammonia-laden water.

Why the ammonia half of the formula matters more than most keepers realize

Clams are a form of livestock that filters water and produces waste like any other animal. A few individuals in a small tank add a real bioload, and the nitrogen cycle is what keeps that load from becoming toxic. Detoxifying ammonia buys the animal time while the biofilter catches up, and it makes new-tank setups far less punishing.

I use it for water changes too, not just fills. A half cap per 25 gallons at each change keeps the tap-water shock out of the tank entirely.

Where it is not the right tool

Prime is a conditioner, not a filter and not a medication. If ammonia is being produced faster than your biofilter consumes it, the bottle only delays the problem. In that case the missing purchase is biological media and a larger filter, not more conditioner.

2. Aqua Natural Oolitic Aragonite Sand - The Sand That Holds Your pH Still

A clam is a calcium carbonate animal living in a calcium carbonate shell, and it is sensitive to a pH that swings rather than to a pH that sits slightly high. Aragonite sand is the substrate that solves the swinging problem, because the carbonate in it dissolves into the water and holds the reading steady through the day.

Buffers at a stable 8.2 according to the manufacturer, and reviewers consistently describe the tank as clearer and more stable after switching to it. The grain is fine enough for a clam to bury into within a few minutes of being placed, which is the behavior you want to see from an animal that just got moved.

Two things to plan for. Carbonate sand clouds the water on day one and it can stay cloudy until the filter works through it, so add it to an already running system rather than a bare tank. And because grains are fine, keep a sponge prefilter on any intake in a tank with burrowers. I also note the listing is aimed primarily at marine systems, though the chemistry is exactly what a hard-water freshwater clam wants.

Surface area is the hidden benefit for your biofilter

The stated surface area of over one million square centimeters per kilogram is what makes aragonite do double duty. Nitrifying bacteria colonize the intergrain space, and that bacterial population is what keeps ammonia low enough for the clam to survive long term. You are buying a substrate and a biofilter housing in one bag.

How deep the bed should be

A minimum of two inches is enough for a small pea or golden clam to disappear completely, which is normal and healthy. Deeper beds are unnecessary and make siphoning harder without giving the animal any benefit.

3. Fluval BioMax - The Biological Load That Keeps Ammonia Off Your Clam

Clams add to your bioload, and a biofilter that was already marginal will start showing ammonia after you add them. BioMax is the fix I reach for because it is cheap, long-lasting, and has one of the strongest rating profiles of anything in this roundup at 4.8 across nearly eight thousand reviews.

Reviewers describe clear water and stable biological filtration, and the media does not alter water characteristics, so it will not interfere with a substrate you have already chosen for buffering. It fits the Fluval filter series from the 104 through the 406 along with the FX5 and FX6, and the same media works in a freshwater or a saltwater canister.

The limitation reviewers mention most is bulk. The rings take up more volume than floss or pads, so in a small filter housing they can choke the flow path. And the media only works with decent flow, which ties it back to the gentle-but-present circulation a clam tank needs anyway.

Why a mature tank matters more here than anywhere else

The manufacturer advises replenishing only half the media at a time so the new material can be properly seeded. That advice exists because a sudden full swap strips a large bacterial colony and the tank needs days to recover. For a clam, those days can be the difference between burying and floating.

A cheap insurance policy for a new tank

If you are setting up a tank specifically for clams, running this media from day one shortens the cycling period considerably. Pair it with a pre-seeded substrate and you remove most of the guesswork.

4. Aqua Natural Sugar White Sand - The Pre-Seeded Bed for Planted Tanks

This is my pick when the tank is planted and the substrate has to do two jobs at once. The sand arrives pre-soaked and seeded with live nitrifying bacteria, which means no rinsing and a meaningfully faster start than a bag of plain dry sand.

Reviewers like the bright appearance in a planted aquarium and the fact that the grains are heavy enough not to lift into a gravel vacuum when you clean. That last point matters more with clams than with any other livestock, because you will be siphoning the sand they live in far more often than usual.

The complaints are consistent enough to plan around. A five pound bag does not go as far as people expect, so budget for more than one. The water can stay cloudy for a couple of weeks after addition. And it is not truly white, it reads cream, and it carries small black and brown flecks that some owners do not like.

Grain size and what a clam can do with it

The grains are fine enough to fall through a net mesh, which is excellent for catching uneaten food and detritus before it rots. It also means the clam can bury itself quickly and completely, which is how it feeds most efficiently and how it avoids light.

Use it as a top layer in an existing tank

The manufacturer lists it as usable as a primary substrate or as a cap over another. That matters for established tanks, where replacing an entire substrate bed is a large project with no upside.

5. Hygger Double Sponge Filter - The Gentle Current a Clam Actually Likes

Clams do not like still water, because still water means the particulate food they filter settles to the bottom and never reaches the gills. They also do not tolerate a blast of current across the siphons. A sponge filter lands in the sweet spot, and this medium unit handles tanks between 15 and 55 gallons.

The 60 PPI sponges give a fine bubble stream, which raises oxygen transfer without creating a violent surface boil. Reviewers consistently praise the quiet operation and the fact that spare sponges and a bag of ceramic media balls are included, so you can rotate media without a separate purchase.

The limitation is the parts list. You will need an air pump and airline tubing, and neither is included, and the flow rate is driven entirely by how far you throttle the air. It also will not polish water to fully clear on its own, so it is not a replacement for a canister or a hang-on filter in a larger system.

Where to point the outlet relative to the clam

Aim the outflow across the tank a few inches above the sand rather than directly at the animal. The extendable and rotatable outlet tube lets you set the stream above or below the waterline, and I run it just below the surface for a ripple that keeps detritus moving without burying the clam spot in flow.

Why it is the right quarantine choice

A new clam should be held separately for two to three weeks before it goes into the display tank. This filter runs a whole small container on one air pump, and its fine sponges mean a smaller companion animal cannot be sucked into the intake.

6. API 5-in-1 Test Strips - The Cheapest Way to Catch a Problem Early

Clams do not advertise illness. They close up, sit still, and slowly fade over weeks, and by the time you notice something is wrong the cause has usually been in the water for a while. Weekly testing is the only way to catch that, and strips are the fastest way to build the habit.

These cover pH, nitrite, nitrate, carbonate hardness and general hardness in one dip, and the sealed strips stay dry in the tube until used. The color chart is readable while the strip is still wet, which matters more than it sounds, because the colors keep shifting after you pull it out.

There are two limits worth knowing before you lean on them. These do not test for ammonia, which is the parameter I would most want to know about, so you need a separate ammonia test. And the low end of the nitrate and nitrite scales is hard to read, because the pinks are close together, so treat a very light result as approximate.

How I use strips on a clam schedule

One strip every week, plus one every time you make a large water change or add a new livestock animal. A weekly pattern gives you a baseline that makes a sudden change obvious, and a large parameter swing is more dangerous to a clam than any single reading.

Pair them with a liquid test, do not replace them

Strips are a screening tool. When something looks off, confirm it with a proper liquid kit before you change course, because acting on a misread color sends you chasing the wrong problem.

7. Weco Wonder Shell Mineral Tablets - Chlorine Removal Without Liquid Dosing

These tablets are for the small, occasional job: a top-off on a tabletop nano, a sudden bucket of tap water, or a water change on a tank where measuring a fraction of a milliliter is impractical. They are made from natural materials, remove chlorine instantly, and they do not require a dropper or a dosing calculation.

For a nano tank where a clam shares space with a shrimp colony, the simplicity is genuinely useful. Reviewers rely on them for fast treatments and clearer water and the format leaves no mess behind.

Two things to weigh. Three tablets is not many treatments, so if your tank needs regular top-offs you will go through packs. And tablets add mineral load in a way that a liquid conditioner does not, and they give you less control over the dose, which on a small tank can mean more mineral than the water needs.

When to reach for tablets instead of a liquid

Use a tablet when the volume is small, the dose would be a fraction of a capful, and the water change is routine. Use a liquid conditioner when you are filling a larger volume, dosing a new bag, or handling a larger animal, because the concentration and control are better.

How to spot a genuine chlorine event

If a fish is gasping at the surface right after a top-off, you have a chlorine problem and you need to act on it immediately rather than wait for a test. A tablet dissolved in the affected water gets the reading down in minutes.

8. API Carbonate Hardness Test Kit - The One Parameter Most Tanks Skip

Alkalinity is the parameter that decides whether your pH is going to hold steady, and a clam is a calcium carbonate animal that suffers when pH swings. Many routine test kits report hardness but not carbonate hardness, which is why I keep this one in the closet regardless of what else I own.

The method is a simple drop count where one drop equals one dKH, compared against a color card. The kit includes the solution, the card, and a capped test tube that matches the tube size used by other kits in the same range, so you are not hunting for a different tube at midnight.

Reviewers find the reading accurate and the method easy once you have done it a few times, but they also flag the instructions as the weak point. Misreading the drop count is easy and produces a badly wrong conclusion, so watch a walkthrough the first time. And in very hard water, each test consumes more solution than in soft water, so the bottle lasts less time than the label suggests.

Stability beats a specific number

The goal is a carbonate hardness reading that holds steady week to week, not a magic figure. A tank bouncing between a low and a high reading every few days is a dangerous environment for a clam even though both numbers look acceptable on their own.

What to do with the result

If the reading is low, the fix is usually a buffering substrate rather than a chemical additive. If it is high and swinging, a partial water change with treated tap water is the standard correction. Test first, then act.

9. AQUANEAT Air Stones - Cheap Surface Agitation That Feeds the Tank

A clam does not need a powerhead aimed at it, but it does need moving water. A gentle bubble stream does two jobs at once, adding oxygen to the water and keeping fine detritus suspended long enough for the animal to filter it instead of letting it settle.

These produce dense, tiny, steady bubbles rather than a coarse froth, and at 0.55 inch by one inch they fit under most filter intakes without taking up visible space. A twelve pack means you always have a spare, and a clogged stone gets replaced instead of being cleaned under the tap.

The maintenance is simple but not zero. Soak them for about thirty minutes before first use so the pores clear, and brush them periodically to keep mineral and algae deposits off. Skipping that is how an air stone turns into an algae farm.

Placement matters more than quantity

Run the stone near the back of the tank or under the filter intake, where the fine stream suspends debris and drives it toward the filter. Put it directly above the clam and you create a patch of disturbed sand the animal will have to fight to stay buried in.

How much flow is too much

If the water surface is visibly churning and the sand is shifting, turn the air down. The goal is a gentle ripple you can barely see from across the room, not a boiling surface.

10. Carib Sea Super Natural Sand - The Brightest Bed for a Small Tank

Visual clarity is a real consideration in a small display tank. A bright white, pH neutral sand makes the animal and any inverts on top of it easy to see, which matters if you are checking whether the clam is open and feeding or has clamped shut.

It is pH neutral for both fresh and salt water, contains no dyes or paints, and the very fine grain suits bottom dwellers without injuring their barbels. Reviewers also report solid plant growth, in some cases without added fertilizer, which is a useful surprise in a sand bed.

The caveats are well documented. It needs thorough rinsing or the water can stay cloudy for weeks. Fine grains get drawn into filter intakes and vacuumed up easily, so use a prefilter. And the sand shifts from white to a light tan once it is in the tank, so the bright look is a first impression rather than a permanent state.

Choose this one for looks, aragonite for buffering

These two sand options solve different problems. If your tap water is already hard and your pH is stable, the bright neutral sand is the better aesthetic choice. If your water is soft or your pH drifts, buffering substrate matters more than appearance.

Rinsing routine that saves you a cloudy week

Rinse until the water runs completely clear, not just until it stops looking brown, and let it settle in a separate container with dechlorinated water before you pour it in. Rushing this step is the single most common cause of a long cloudy spell.

11. ALEGI Sponge Filter Pad - Cut-to-Fit Media for Custom Filtration

Standard sponge filters are fine until you want something shaped a specific way, and that is where cut-to-fit media earns its place. This pad slices to whatever footprint your DIY filter, sock, or sump compartment needs, and it is the cheapest way to solve a sizing problem that would otherwise mean buying a whole new housing.

Reviewers like the durability and report washing and reusing it many times, plus a pleasant detail that it springs back to full shape after a hot soak and a short cycle in a dryer. The pack also runs larger than expected, which gives you enough material for more than one compartment.

The value per pad is lower than buying bulk foam, and it arrives vacuum sealed and compressed, so it needs hot water or a dryer run to regain its thickness before you cut it. Some users with larger housings report wanting a thicker variant instead of the one inch.

Why mechanical filtration matters around a clam bed

Fine sand in a tank gets stirred up by anything that moves, and a clam in a bare area of substrate will draw that sediment across its gills constantly. A mechanical pad in the path of that sediment keeps the water column clear before it reaches the animal.

Use it as an intake prefilter too

Cut a piece larger than the intake opening, slit it down one side, and slip it over the strainer. It stops the finer sands and the heavier grains from being pulled into the impeller, which is the most common way a burrowing animal kills a filter.

12. SunGrow Shrimp Calcium Powder - Mineral Support With a Real Caution Label

I am including this one because inverts sharing a tank with a clam need a calcium source, and clams are frequently kept alongside shrimp rather than alone. I am also including it with a caution, because it is the lowest rated item here at 3.9 and a meaningful group of users report exactly the outcome you do not want in a small tank.

On the positive side, breeders report better molting, brighter shell color, and increased breeding success, and the powder typically clears within a day. Only a small amount is needed per dose, so a 1.8 ounce pack lasts.

On the negative side, over-dosing clouds the water and coats surfaces in white dust, and several users report a pH spike after dosing as directed. Uneaten powder has to be cleaned up because it will alter pH on its own. Use it in a planted or larger tank, and never in a nano where a pH swing has nowhere to go.

How I would use it here

Dose well away from the clam, remove what is not eaten within a short window, and check your pH the next day before you repeat. A clam already sitting in a stable tank is sensitive to a sudden change, and this is the one product on the list that can deliver one.

A better alternative in most cases

If the tank already has a calcium carbonate substrate, you may not need a supplement at all. Solve the mineral question at the substrate level and you remove a variable rather than adding one.

Do Freshwater Clams Need to Be Fed?

The short answer: a healthy freshwater clam in a mature, well-lit tank usually does not need supplemental feeding, and the store advice that they need only light and warm water is incomplete rather than wrong. It leaves out the tank-maturity requirement, the sand bed, and the parameter stability that decide whether the animal survives the first month.

The genuine debate in the hobby centers on phytoplankton, and it is worth separating what is settled from what is not. Experienced keepers on Reef2Reef argue that clams meet their nutritional needs through photosynthesis combined with what they filter from daily fish feeding, and that the more important external input is nitrogen and phosphorus, which routine feeding already supplies. The claim that smaller clams physically cannot take larger particles has been debunked repeatedly in published work, and a keeper with commercial clam farming experience states that adequate light is the main requirement.

That is a settled argument in one direction, and I want to be honest about where I land. Live phytoplankton is inexpensive insurance, not a rescue. If your tank is clean enough that a siphon removes nearly all uneaten food, there is very little suspended particulate for the animal to filter, and adding a small dose of live culture is the cheapest way to close that gap. Keep the pumps off, add a dose, and let the tank settle. If it is live, nothing in the tank is harmed by it, and other filter feeders use it too.

Pastes are a weaker option for the same reason. A concentrated paste clumps its cells together, and a small clam gets less from a clump than from an evenly dispersed live culture. If you feed, feed live.

What actually kills clams is far more often a mature-tank problem than a feeding problem. A newly set up tank with an unfinished cycle, unstable alkalinity, a swinging pH, or a blast of current is a harder threat than an empty stomach.

What Freshwater Clams Actually Need to Survive

Five conditions, and a tank that meets all five is one where a clam is genuinely low effort. A mature cycled aquarium, a soft sand bed it can bury into, gentle circulation with no direct blast, light bright enough to support photosynthesis, and stable alkalinity and pH. Miss any one of them and the animal will usually decline over a few weeks rather than immediately, which is why the failures are so hard to diagnose.

The mature tank requirement is the one beginners skip. A clam placed into a tank that has not finished cycling is exposed to ammonia it cannot escape, because it filters that same water through its body continuously. Wait until your tests read zero ammonia and zero nitrite consistently across a couple of weeks.

Light matters more than most freshwater keepers expect. These are animals that evolved in bright, shallow zones, and a clam in a dim corner of a planted tank is a clam on a slow decline. Aquarium hobbyists running clams report roughly 200 PAR as a bare minimum and real visible growth at 300 and above, so position the animal in a lit area rather than behind a piece of hardscape.

Stocking is another common error. Clams are animals with bioload, not decoration, and they produce waste like any other livestock. A rough guide is one clam per ten gallons in a well-filtered tank, and fewer in a small or lightly filtered one.

How to Set Up Freshwater Clams in a Mature Tank: 5 Steps

1. Confirm the tank is ready. Zero ammonia and zero nitrite on two tests a week apart, and stable pH and carbonate hardness. If the cycle is not finished, wait.
2. Prepare the substrate. Add a soft, fine sand bed at least two inches deep across the area where the clam will live, and put the tank on a flow rate that keeps the surface gently rippled.
3. Acclimate the animal properly. Float the sealed container to equalize temperature, then transfer the animal to a clean container. Add tank water to the shipping water a small amount at a time, several times over an hour, before the animal goes in. Skip the float-and-dump method.
4. Place and observe. Set the clam on the sand at an angle rather than dropping it flat, and leave it alone. Within minutes to an hour a settled clam begins to bury itself, and the foot pumping through the sand is normal behavior, not distress.
5. Watch for two weeks and feed only if needed. A buried clam with a firm shell and a periodically open valve gape is doing fine. If the tank is very clean, a small live culture dose once the pumps are off is reasonable insurance.

Why Your Freshwater Clam Keeps Dying

Almost every clam loss falls into one of these six patterns. Work down the list and you will usually find the category before the animal is gone.

It sat on top of the sand, never buried

A clam that will not dig is almost always rejecting the substrate or the water. Rough gravel, a bare glass bottom, or a bed that is too shallow will keep it exposed, and an exposed clam gasses and dries. A fine sand bed at least two inches deep fixes this.

It floated to the surface or sat in one spot

Gas buildup in the mantle and an incompatible water chemistry both cause this. A tank with unstable alkalinity and swinging pH is the common root cause, and a carbonate buffering substrate plus regular water changes is the correction.

It was in the tank too early

Adding a clam during or shortly after a cycle exposes it to ammonia for weeks with no escape. This is the most common beginner error and the one the seller at the counter will never tell you about.

It closed up and never reopened

A permanently closed valve in a mature tank points to chemistry, a sudden parameter change, or a temperature swing. Test ammonia, pH, and hardness in the same day, and consider the last large water change you made.

It disappeared overnight

This is predation, not disease. Assassin snails, crayfish, and some fish hunt bivalves. Quarantine new arrivals, check the tank nightly for a while, and keep a camera pointed at the sand bed so you can confirm what happened.

It was fine for months and then declined

A long slow decline usually means the tank changed around the animal: new fish that altered the bioload, a heater malfunction, a large unconditioned top-off, or an algal crash that removed the food supply. Weekly strips catch this weeks before the clam shows it.

How to Choose Freshwater Clam Supplies

Judge every purchase against one question: does this help the clam open, feed, and stay buried? Anything that does not serve one of those three is optional. This is how I evaluate every item in this roundup.

Grain size and buffer capacity in a substrate

Fine grain is what a small clam can actually push through with its foot. Coarse gravel, lava rock, and large pebbles are all wrong for a bivalve that spends its life in the bottom layer. The second question is buffer capacity, and that is where aragonite separates itself from neutral sand, because a stable pH is worth more to a clam than a bright tank.

Reading a light reading before you position the animal

PAR is photosynthetically active radiation, the light band plants and photosynthetic organisms actually use. If you have a light meter, roughly 200 PAR is the practical floor for a clam and 300 or more supports visible growth. Without a meter, the practical test is whether the spot stays in bright light for most of the day rather than sitting in the shadow of a filter outflow.

Flow rate, and where the outflow points

Enough current to keep particulate suspended, not enough to sweep the sand out from under the animal. A sponge filter or a throttled canister outlet handles this, and aiming the stream across the tank instead of at the clam is the single most useful adjustment most keepers never make.

Test gear that measures what actually kills clams

Prioritize ammonia, carbonate hardness, and pH stability over anything else. Strips give you the routine baseline in seconds and a titration kit gives you the accurate number when something looks wrong, and that pairing is more useful than any single expensive meter.

Transport gear is not optional

Clams are sold bagged, and a sealed bag is a hostile environment for an animal that filters water. A container you can drip tank water into gradually, plus a working acclimation plan, is the cheapest insurance in this entire list and the place most first-time buyers skip their preparation.

Frequently Asked Questions

Conclusion

If you are starting from nothing, buy in this order: Seachem Prime to condition the water, a soft fine sand bed, biological media, and weekly test strips. Those four cover the majority of the reasons clams die in home aquariums, and the rest can follow once the animal is settled.

Where the priorities differ, match the pick to the problem. Chase stable parameters and a clean biofilter and the Fluval BioMax and the API carbonate hardness kit are the two that earn their place. Prioritize gentle circulation and a quarantine setup and the Hygger sponge filter handles both. Want a bright display tank and the Carib Sea sand reads best once rinsed properly.

Seachem Prime is our overall pick for best freshwater clam supplies because it conditions the water, buffers against ammonia, and is forgiving to dose, and that combination protects the animal in the window where most losses actually happen. Pick your setup, give it a mature tank and a sand bed, and check the water weekly.