Rtifs

Ok. I set up my first NPT last weekend. 75g, unfertilized topsoil (seems to have lots of compost). It’s actually not completely setup yet… needs more plants, but I’m trying to get the ground cover plants (dwarf hairgrass (Eleocharis acicularis) and pygmy chain sword (Echinodorus tenellus)) a head start over the amazon swords that I’ll be moving into it.
My question is what happens if the soil is deeper than 1”? Mine is probably 2” and maybe 3” in a couple spots. This soil is quite fluffy though, so it could probably compact down by an inch. I’ve read “Ecology of the Planted Aquarium,” but don’t remember what happens with deeper substrate. I’m assuming deeper substrate is in danger of becoming anaerobic and thus toxic. Are there any plants that can help aerate the soil other than lilies (too big for aquarium environment)?

mudboots

My first attempt at an npt was using organic substrate ranging from 2 to 4 inches deep. The entire tank was toxic from the methane and hydrogen sulfide gas and so on. I had to completely tear down the tank, and was thankful that it was only a 20 gallon and not the big tank.

The other npt tank I set up, that has not had any toxic gas issues, has about .75 inches of organic substrate (loose and "fluffy") with another .75 inches of a sand/gravel mix.

If you compact your substrate you restrict aeration and promote the anaerobic conditions that will lead to toxic gas production.

Right, wrong or indifferent, my humble suggestion would be to re-do the substrate to where you have between .75 and 1 inch (but no more than that) of the organic substrate, with a similar depth "cap" and not let your totol substrate depth be greater than 1.8-2.0 inches.

HoldingWine

You might also want to measure the substrate depth accurately with tape measure or the like. I noticed when I guestimated soil depth, I often ended up overestimating how deep my soil was. If the deepest part isn't over 1.5", I wouldn't worry about it, but if you did see spots that were in the 2-3" range, you might want to consider redoing the tank.

Definitely find a few Malaysian Trumpet Snails if you haven't already. They're great for aerating the soil. I'd recommend throwing in those sword plants, too. They can help suck up some of the excess nutrients from a large soil depth.

How about a picture of the tank?

dwalstad

I doubt that your small, ground cover plants will grow well enough to help stabilize a 75 gal with a deep organic substrate. I would plant large robust plants (Red Tiger Lotus, several Amazon Swordplants, Giant Val) as soon as possible. You'll want to encourage emergent growth. For these plants, you'll need very intense lighting.

Folks, this is why I generally recommend 1" of soil and 1" of gravel or sand. If you go with a deeper substrate, you need to match it with intense lighting and robust plants right from the get-go.

Dustymac

I didn't know better when setting up my npts so naturally my thought was if 1" is good then 2" is better. Fortunately the initial plantings included lots of Swords and explains my success so far. But I'm wondering if there is still a possibility for problems in areas of my tanks where the Sword roots might not reach?

Jim

Perianth

While we are wondering, I have been wondering if deep substrate produced hydrogen sulfide is hazardous to us humans. I know it can be fatal in extreme cases such as at oil rigs (have heard of a public evacuation because of that), but I have also read exposure causes visual problems. I don't believe I want any of it in my house. Any body have any facts on what the danger is?

Diana K

No facts or studies, but my guess is that a house is too well ventilated and the production is too small to cause problems.
This may not apply to an enclosed fish room, though, where you are minimizing air exchange to maintain temperature.

dwalstad

H2S (hydrogen sulfide) gas has been shown to be more toxic than ammonia to mammals.

That said, plant roots and bottom-dwelling fish are on the "front-lines" from any H2S generated by organic substrates, not you. Many aerobic bacteria quickly oxidize toxic H2S to harmless sulfates. By the time any remaining H2S escapes into the air, its concentration is severely diluted.

Unless your house positively reeks of the rotten egg odor, I wouldn't worry about H2S as a poison to you.

However, you do need to monitor your fish and plants. Are plants floating to the surface with blackened roots? Are bottom-dwelling fish becoming lethargic?

Rtifs

Ok. Well no worries, since I don’t have anything but water and plants in it now. I’m in the process of moving, and the tank is at the destination. I won’t be there full time for close to a month, hence the lack of anything in the tank that needs regular feeding. My plan was just to try and get the substrate through the worst of the “chaos” break-in period before needing to move my fish in. Unfortunately, when I set it up, my time was very limited and I was in an incredible hurry. That’s why I was careless with the substrate depth.

I may be at the apartment again in two weeks, so I can drain and redo the substrate then. Here is a pic I took today after adding one large and several small swords. The water’s a little cloudy, but I’m not worried about it at the moment… especially if I’m going to drain it soon.

Attached Thumbnails

 

Qwertus

The substrate looks average to me for a tank that size. It isn't too deep.