KH dropping in shrimp/snail tank

This may seem like a silly question but do snails use up the calcium carbonates in the water causing it to lower the kh?

It's a 80 litre cube. Probably only 64 litres of water with rabbit snails in. I have 5 adults and about 10 babies. The water is incredibly soft round here. I dose with salty shrimp gh/kh plus. The gh stays at 8 and kh is 4. I change the water every 5 days. After 5 days I tested and the gh was 8 and kh was 2. Should I add crushed coral to try and keep the kh up at 4? I have some spiderwood in there unless that's lowering the kh by making the water more acidic

 

yes, that sounds like a plan, it's not a silly question, yes snails use up calcium from the water to build shells., if you add crushed coral, just keep in mind it will lose it's buffering ability and get depleted in 6 months to a years time, you'll see it when a drop occurs later on down the road, so I don't know if you'd want to just add the crushed coral to the substrate, or segregate it in a porous bag ect for an easy exchange when you need to.

do you have anything else in there? Shrimp, crab, crawfish will use some calcium, all fish use it for bone growth and bone density.

I hear cuttlefish bone (sold at some aquarium places) works similar to crushed coral. when the hardness drops it dissolves and releases calcium to bring the hardness back up. same scenario as the crushed coral except it's most all calcium and will dissolve completely and you'll know to add another piece when it does.

Snails are big consumers of calcium and with there ability to reproduce can deplete a tank without some form of calcium supplementation.
FIsh would do fine getting it from the water and foods, snails not so much when you factor in the reproduction rates.
And dead snail shells will break down again into calcium if left in the tank, however, dead snails themselves decomposing are bad for the Ammonia and Nitrites and nitrates.

the spiderwood might be part of the problem, I'm not sure, I know it's a soft wood, they can leech tannins and lower pH, and if you lower pH kH will go some with it. I dont' know how much of an effect this is having or not having though in your situation. but the combination of factors at play might be the reason you are experiencing what you are.

 

Anyone have trouble with the API GH/KH test kit? My issue is getting the reading.

 

Plus one on the cuttlebone. I use it frequently in my shrimp tank. Yes, snails use it from the water. However IMO general hardness is more important than alkalinity when it comes to snails specifically

 

The water out of the tap is gh 2 and kh 1 or non existent. Ph is 6.6. The salty shrimp raises gh to 8 and kh to 4 and ph to 7.4. I was just shocked to see the kh drop so low after 5 days. I have crushed coral in my main tank to buffer the water and keep ph at 6.8/7 and I have crushed oyster shell in my pond to keep ph at 7/ kh of 2.

I may have to feed them more. I feed spinach and cucumber twice a week

 

Yes KH will always go down, anything acidic will make it go down and lots of acidic things are produced constantly in a tank.

I may have to feed them more. I feed spinach and cucumber twice a week

The breaking down of waste is acidic so feeding more = faster KH depletion

 

It definitely seems like I need to add some crushed coral to the filter to hopefully stop as steep a drop in kh

 

Most important thing with snails and shell health is keeping the pH above 7. Things like kH and gH can always be supplied in the diet too. I think what you’re doing now is fine… if you add or change too many things it will probably do more harm than good.