Home made Black Water Extract

by Francesco Zezza

Foreword: once back from the Amazon forest I needed to deal (for the first time) with fishes coming from water with a chemistry ranging from moderate to highly acidic (although I deliberately avoided those which were extremely demanding in this aspect). Of course the first step was to rely on products available at my pet-shop which proved to be expensive (to buy) as well as perfectly working.

I kept thinking of why the acidic water (aka known as Black Water and/or Cola Water) happens to have that "given" chemistry. It took some time to reach the conclusion that – apart from rain water – key inputs were (in the wild) fallen and decomposing leaves (from the forest canopy) and broken branches (of the same origin). The element which gave me the solution was the plastic bags filled with "leaves collected in the Amazon" (which I believe was a true claim) that I saw on sale in Hustinx petshop (during our MCH meeting held in Belgium some years ago)

Secondly, I always thought that leaves are more or less the same everywhere in the world (same seemed true for wooden branches) which was further supported by the fact that the bogwood pieces used to aquascape tanks give an amber /brownish colour to the water irrespectively of where they come from.

I kept thinking for a bit longer and than started experimenting: to make a long story short I ended up with the following recipe:

• Get 15 large, dry, oak leaves. Be absolutely sure that the leaves you are using are clean: this means there should be no insect’s eggs or pollutants of any kind on them ! If in doubt discard them.
• Dip them in a pot containing 1.5 liter of water (Rome's tap water worked perfectly well for this project).
• Leave them there for 24 - 48 hours.
• Boil the pot for 15 minutes.
• Let it cool.
• Filter the water through a coffee paper filter (to trap detritus or any other insoluble matter - just in case …)
• Store the liquid in plastic, dark bottles (you can use any kind of bottles and preferably empty water conditioner canisters).
• You’re ready to go.

Oak leaves still on their branch(es). This is how a suitable leaf looks like

You’re done. My pH readings of the water before and after this process showed a decrease in the pH value of 1.0. The tricky part is to determine how much from this extract you have to add to the tank (and the water used for water changes afterwards). I am sorry but there is no rule for that. You will have to evaluate this yourself since no two extracts are the same not to mention the differences in the tap water.

Final remarks:

1. Adding a big bogwood will help, too. A lot of tannin and other favorable substances will be released in your water.
2. The boiled leaves can be added in the tank, too (they may float at first but will slowly sink after a while).  Loriicarids,  always searching for fibers,  will happily chew them.
3. Of course you must forget the "crystal clear" water of your Malawi tank, but you have to keep in mind that you are replicating a biotope which is radically different from Lake Malawi.

Needless to say, my petshop didn't enjoy this "trick" that much. However, my Amazon fishes did ! Many of them are still (in 2004) happily swimming in my tanks. Give it a try - it will save you some money …