Deep sand bed in freshwater tank?

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R

rustyspurs

Candiru
MFK Member
Nov 30, 2009
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ballynahinch n. ireland
Hi,
I built a 220 gallon ply tank over a year ago which has worked perfectly so far. However I failed to consider how much of the fish behaviour I would miss as I can't see the bottom of my tank while sitting on my sofa.
I need a substrate which is 4inchs deep to bring the bottom of the tank to eye level and have play sand in the tank already. I like the sand as it compacts after a few days and doesn't allow any waste to penetrate the top layer.
My worry is the debate fish keepers seem to have in relation to deep sand beds in FW tanks, some say its perfectly safe while others reckon that gas will eventually build up and kill all the fish.
Has anyone got any first hand experience about this?
Thanks in advance,
Paul
 
First hand experience no but gasses can build up under a deep sand bed. The way to prevent that is get a fish that digs a lot or just disturb the sand once or twice a month during wc.
 
Yeah I used to stir the sand in an old marine tank once a month but I've read from a few sources that a freshwater setup can be left alone. One stated that using loaches to stir the top inch of a DSB is all you need.
The problem is that no one seems to know for sure, I'm like you and have heard of the dangerous build up of gas and the need to stir it. But recently I've read arguments that the filtering bacteria in the substrate naturally breaks down the gas build up.
It seems to me that these gas build ups would occur naturally in river beds.
I'm just going to go for it and see how it goes,
I'll post the results in a few weeks
Cheers
 
If you are going to go with a deep sand bed in a freshwater aquarium, get some malaysian trumpet snails. They will aerate the sand bed. However, once you have them they can overpopulate the tank.
 
I wiped a 120g tank full of Geophagus and Metynnis a couple of months ago. Hadn't done proper tank maintenance in some time to be honest, and thought I would try to make up for lost time. Next thing I know I get a sulfur smell, the fish start darting around and dropping like flies. In the end, I was left with one geo that had a burn on his caudal peduncle...so yes it can be a problem. But to be honest, I got what I deserved (can't say the same for the fish :(). Give the sand a stir from time to time and you'll be fine.
 
I had a tank with a large, obtrusive frame a number of years ago.
I used a plenum (popular back then in deep sand salt water tanks) framed with 1" PVC with drill holes, covered in screen, that provided an extra 2" of raised space, and that, covered with 2" of sand.
The plenum seemed to prevent hydrogen sulfide buildup, because although the sand covered the plenum, the area underneath the screen was anoxic as opposed to totally anaerobic.
I also had/have Malayan snails which do a great job of keeping the sand bed mixed.
 
I have a different opinion on a couple remarks. It seems that people do know for sure what happens with a deep stagnant substrate and I'm not sure that anyone says it's perfectly safe. Of course, it could be the same way that some people mean that "lions are perfectly safe as long as they are caged behind 18 foot fences", then yes, the deep substrate is 'safe.' The debates are over exactly where the anaerobic bacteria thrive but there's no debate that they will thrive if given a stagnant substrate that is deep enough.

The idea is to either keep it shallow or if it's kept deep to either regularly aerate it or to never touch it. Depending on your livestock and cleaning practices, you may find the lower substrate leaking toxins if you opt for the deep substrate-never touch approach.
 
Yes it can build up and release. Ive personally seen it kill fish. I highly recommend the Malaysian trumpet snails to help. They will burry deep and shallow and work through the substrate. That and when doing water changes probe the substrate nice and deep on a regular basis. Just doing the substrate cleaning weekly will make all the difference.

Sent from my SPH-L710 using MonsterAquariaNetwork App
 
Thanks all, some great advice here.
I will add Malaysian trumpet snails and be sure to mix it a little at least once a week.
I'll post a pic in a few days with the deep sand to show the before and after look, it,ll really make a difference to the viewing experience so thanks :)
 
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