Hi everyone,

It occurred to me that some other list members might be interested in the following recipe, so I decided to have a go at posting it, even though I might appear to be breaking an open door - see below...

A couple of years ago, I decided to try and formulate my own tank water "from scratch". So I did a careful search of the scientific literature in the field of fresh water organisms and plants breeding and came up, after some calculation, with a mix of dry salts which I can add to pure water to get a perfectly reliable "average" or "typical" fresh water composition... only to realize that such thing are commercially available in any good shop!

Still, because of the price of such commercial products, I decided to go on with my own brew, and it has proven very successful for me (I used to have a lot of algae problems and very poor plants, and now my problem is rather to get rid of the plants!) So, here it is.

Excepting the calcium sulphate, all salts are anhydrous. If using a hydrated version, correction must be made for the water content of the salt. Hydrogenocarbonate is synonymous with BIcarbonate, but plain carbonate definitely won't do! Mix the dry salts thoroughly, as each spoonful of the powder must have the same composition as the total, and keep it dry in a tightly closed container, as it will absorb moisture and get sticky in the process.

I add 7 (seven) grams of salt mix (that's a biggish teaspoonful) to 10 (ten) litres of pure water. This gives a GH around 10, and KH 5 (it has been formulated to yield a KH value half of the GH value). If you want higher or lower, use more or less in direct proportion. pH typically is 7-7.2 reaching 6.8 when I use (DYI) CO2. I use osmosed water, but rain water from an unpolluted area would be fine if it has not been in prolonged contact with metals or concrete.

Do not use tap water: THIS IS NOT AN ADD-ON FERTILIZER. It MUST be added to chemically pure water, outside the tank. The salt mix dissolves immediately, but do not try to make a concentrated pre-mix, with the idea of diluting with more water at the last moment: it will likely precipitate.

Naturally, you will NEED to add trace elements. I use the "poor man's dosing drops" or PMDD recipe I found on the Krib (Tim Mullins site) at the recommended dosage, which I follow by analysing for iron content in the tank a few hours after partial (10 %) water changes 2-3 times a month.

My substrate is pure sand and small gravel (that admittedly got somewhat dirty after several years in that same tank) and still most substrate-feeder plants do quite well.

Phosphate is now completely under control at 1 ppm +/- 0.5 (only source is fish feed) and I follow nitrate concentration (usually 20 - 30 ppm - again only from feed) now and then to make sure I do not need to add more (which I don't, but it all depends on the number of fish, and how much you feed them). If I did, I would add some potassium nitrate. A commercial liquid fertilizer containing trace elements could be an easier alternative.

One last word: if you intend to try this, buy pure chemicals (don't mess up with plaster and road salt or whatever else might be nominally the same product as those I mention) but do not buy the top quality "analytical reagent" or "purissimum" either. Just plain "pure" is good enough and there is a tenfold difference in price.

Now, why go all the way to make your own water? Well it is a matter of completely controlling all parameters in a reproducible way, and stop depending on your tap water quality. I never have to adjust anything any more or add extra fertilizer or whatever else. I do not need to dechlorinate or bother about phosphate building up. All the fish are in outstanding health, as are the snails (ampularia, breeding faster than I can cope!) The experience is now 2.5 year old, and entirely positive. I would not dream of going back!

OK, that's it. I realize that buying chemicals and weighing them with reasonable accuracy is not within everybody's idea of fun and easy, but maybe some of you will want to try. I'll be more than happy to help (off-line?) with more specialized questions.

Be happy,
Philippe