JohnnyOscar wrote:If it is too deep you can get toxic gas building up under the sand. When there's enough of it, it can bubble up through your tank and poison the water.
I've seen this happen in my 180 gallon tank. I put in 1.5" of sand initially, but the fish move it about and soon enough there were mountains and valleys. And after a while I spotted small bubbles coming from the mountains...
There's now a lot less sand in my tank. Fortunately I didn't lose any fish, but the sheer volume of gas I unearthed as I scooped out the sand was quite disturbing.
flyinmike wrote:Curious, how did you know it was toxic?
That's where the discussion sits so far. Anybody else had this occur?JohnnyOscar wrote:I'm guessing it is hydrogen sulphide, it certainly smelled like it: rotten eggs. It can quickly bring down your pH. If your pH is already low, then H2S certainly won't help your fish....
Also, I know that oxygen transfer takes place at the surface. The only thing air bubbles do is agitate the surface to create more transfer area. Is this not true with other gas as well? Wouldn't a ventilated top keep buildups from occuring? To me if you can smell it then it is not mixing with the water but rather escaping. Not to go on and on, but if there is the toxic gas getting in the water would not proper filtration and plants help to control it. I'll stop now so someone else can talk..