Kai Witte

I've been keeping blackwater crypts submersed for decades, often in small breeding tanks and other low-tech set-ups. I never had any problem when their natural environment got reproduced reasonably well:
Rule #1. No carbonates in the water nor in the substrate/mix.
Advice #1. A low pH is your friend.
Suggestion #1. Keep nutrients limiting.
Common sense. Don't overdo lighting.

I'm sure there are dozens of possible ways to do it - I'm relaying just my experiences as some food for thought here...

In my early days, I've usually been using peat to lower the pH (pH 3.5-4.5 is a good target range) of pure rain water (or DI water) and also to add some organic stuff (fulvic acids, etc.). Substrate ranged from pure quartz sand or weathered granite sand to pure peat. Additional nutrients came mostly from fish feeding.

Later on, I experimented a lot to avoid unsustainable use of peat. Adding autumn leaves (beech, oak, maple, etc.) workes quite nicely but you have to account for introducing (also) more readily digestible organic material (most blackwater fishes don't mind unless oxygen levels go down to zero... ).

Nowadays, I usually just use leaf-mold and throw that in a tank filled with DI water. Just kidding? No! This is not for the faint of heart though...

Depending on the quality of your leaf-mold, you have to expect getting some algae but usually the "nasty" ones will get away eventually. You may not want to try this first with a large show tank though.

If you're a bit hesitant, just make an almost fluid leaf-mold slurry and fill the tank 0.5-1 inch (you can use more but it's usually wiser to start with a little and add more later on). Drop in some crypts and let them grow emersed & propagate for a while; also see my thread on emersed culture: http://www.aquaticplantcentral.com/f...crypts-in.html. (Consider adding some more slurry and waiting some more weeks.) Then gently fill the tank completely and, presto, you have a real blackwater habitat!

Good luck!

Kai Witte

Any top layer compacts the leaf-mold. It can work but usually it's not a good idea. Unless you're reproducing a blackwater stream with fast current, you don't need a top layer - just some imagination and possibly several weeks of emersed culture as a head start...

Kai Witte

An example from a tank with lowered water level to allow enough space for flowering...

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Kai Witte

AaronT

Thanks Kai, that was very informative. I'm guessing then that the blackwater species don't need significant flow in your experience? Do you inject CO2 at all or let nature take its course?

ts168

Hi Kai, I have some question to ask about this setup.

1. Is there any pump/filter in the setup to have water movement?
2. Is there any fish inside? I believe the fishes will love the cosy environment. Especially the boraras fishes.

Nice setup.

Kai Witte

I often have a little current in my blackwater tanks but that is generally for the fishes and other inhabitants; the crypts certainly benefit a bit from a little water movement but don't need it. This tank has been "sitting" without pump nor heater for over a year...

Blackwater fish really feel at home in such a tank and I've been breeding species from genera like Betta, Parosphromenus, Boraras, Rasbora, etc. in such set-ups. No fish in this one yet since I'm waiting for Paedocypris. A low density of fish, shrimp, etc. helps to provide some nutrients; don't try snails though!

HeyPK

Kai,

Why is the use of peat unsustainable? Does the peat decay and disappear?

Why is it wiser to start with a little leaf mould and add more later? Do you have too much decay if you add it all at once? Do the plants do bettter if you add it in stages?

Kai Witte

Hello Paul,

No problems with the intelligent use in aquaria but it's the mining of bogs for peat which is unsustainable.

That's an old horticulturist's rule: Plant seedlings, cuttings, etc. in small pots. Once their roots have grown throughout the substrate, move up to larger pots. (There are notable exceptions to this rule though!)

Same-o with crypts, especially if you start with small runners or plants stressed from shipping. If I have large, healthy runners of decent size, I often use regular pots right away. But if either the plants or the leaf-mold are not optimal, starting out with less substrate seems to be the safer, more foregiving approach.

BTW, I do add leaf-mold from time to time to feed vigorous plants.

ruki

So carbonates cause problems?