Aquarium Safe Clay

Has anyone used Amaco terra-cotta air dry clay in their aquariums. I want to redo one of my tanks, taking out the gravel and adding an organic dirt, then top if off with maybe sand. I read that you could add red clay balls to the dirt and I have some osmocote plus that I want to roll into the balls. I was hoping the terra-cotta clay would work. I did find the Amaco Mexican red clay after I bought this terra-cotta clay, but it’s a bit more than twice the price for the package size. Any thoughts? Has anyone used clay in their substrate and if so what kind have you used?

 

I went all natural and ended up sprinkling dried clay into the mix of mud. The clay is what's left from what I found quite a few years ago when my family was on a camping trip, my cousins and I dug it up near a lake. The dirt I collected from the woods. Topped it all off with sand and I was good to go.

I'd say so long as the clay you bought was 100% natural, with no additive it should be safe to use. I'd be careful if you are using red clay. Can't remember correctly, but I think the red clay get's its color from the presence of iron that has oxidized, making it rusty red.

 

Look into montmorillonite clay. It has a really high CEC (cation exchange capacity), which means it can pull nutrients that you dose into the water column and make them available to roots. I believe SeattleRoy uses it

 

HI Crash4hope ,

There are many typies of "air dry" clay on the market, some are wax base, some are resin based, some are oil based....most are toxic.

The Amaco Mexican red clay is non-toxic and does air-dry but is not waterproof and may breakdown over time. It likely has a fair amount of iron oxide in it which is actually good, plant roots will seek it out. If you add Osmocote to it don't overdo, Osmocote releases nutrients much faster in water than in dirt. Also, I would put the clay balls on the bottom, then 1/2" of good dirt, top with 1-1/2" - 2" of a good quality quartz pool filter sand like HTH () Your local Ace Hardware can order it in for you and you won't have to pay shipping.

 

The terra cotta clay does say it's all natural and has the ACMI stamp on the box. I emailed the company to see if they can tell me more about the additives.

I am curious about the montmorillonite clay. Any idea if the Calcium Montmorillonite Clay would greatly increase the ph through the substrate. My tap ph is about 7.6-7.8 so I really do not need to raise the ph.

I've been using some diy osmocote plus root tabs for a few months. The plants have really greened up, started dosing liquid ferts too. So far no problems besides uncovering them while gravel vacuuming. Thanks for the advice though I'll go light with them.

 

HI Crash4hope ,

The montmorillonite clay I use is a calcined (heat treated) Montmorillonite clay product similar to cat litter (which is a Bentonite clay product) however harder and less inclined to breakdown (decompose/turn to mud) over time as cat litter can do. It also has a smaller grain size than most cat litter, a more natural and varied appearance, and is more durable and long lasting. Because it is calcined and hard it would not work to make your clay balls.

10 gallon, Calcined Montmorillonite clay substrate, low light (PAR@30), no CO2 but Excel and ferts

 

That looks really nice. The calcined Montmorillonite I found says it has a ph of 5.6. Does the calcined Montmorillonite affect your ph?

 

HI Crash4hope ,

I am not aware of any high CEC substrate, including the ADA Aquasoils, that does not effect PH/dKH and to some extent dGH. High CEC substrates 'strip' the water of carbonates which results in a lowering of dKH/PH and dGH as well. This can be mitigated somewhat by 'pre-charging' a high CEC substrate with nutrients that the substrate can absorb. Because my water here in Seattle is very soft (<1.0 dKH / <2.0 dGH) I pre-charge my substrate with my DIY Equilibrium to add additional Ca, Mg, and K to the substrate. Even doing that a high CEC substrate may continue to lower the dKH/PH and GH for several months until it becomes saturated and reaches an equilibrium with the water chemistry.

The substrate in the tank of my previous post is Safe-T-Sorb #7941, it comes in 40# bags. Tractor Supply Company currently has it on sale for $5.oo a bag (reg. $6.49). I screen mine through 1/8" hardware cloth to get rid of the 'fines' (smaller particles and some dust) and usually end up with 20 pounds of substrate. There are several threads on the forums The Planted Tank and Aquatic Plant Central regarding using Safe-T-Sorb and other calcined clay substrates in aquariums. Full disclosure this product is clay based, it will never rise completely 'clear' water and the first cleaning prior to use takes several washes.

Here is my 20(H) gallon and 75 gallon with Safe-T-Sorb.