It’s really quite simple. Just bare in mind a couple of things:
1. BB (Beneficial Bacteria) found in an established filter/tank’s water will compete with algae for ammonia and usually win the battle. No BB in your setup please.
2. Provide natural sunlight. If you need to use artificial lighting, make sure the lamp’s output is “daylight”, (6500 Kelvin). You’re on your own if you think “bluish overcast sky” (> 10000 Kelvin) is natural daylight. The lamp must also be intensely bright. Ideally use a Metal Halide lamp if you can bare the heat or have a large tub. You can use a compact florescence lamp (PL Lamp) too if your tub is relatively small and shallow. Most, if not all, normal florescence lamp (FL lamp) will not work, as their output intensity is not strong at all. Make sure there’s UV shield protection; UV kills algae.
3. Go for high ammonia level initially. To some extend the high ammonia level will inevitably stress your fish so start off with some cheap healthy fishes please.
So long as you bare the above in mind, cultivating green water is easy. You just need a little patient as green water does not appear overnight, or we’ll have puddles of green water all over town — areas around your neighborhood wet market, by the Fountain of Wealth at Suntec City, etc. Give it about 2 weeks to appear. Once you get green water, they will bloom much quicker when you use some old green water to seed fresh clean tap water.
Clean your tub/tank. Scrub it clean using detergent/alcohol/atomic bomb or whatever method you desire making sure you have killed all the BB that were previously thriving in it. All right, washing the tank with tap water should do it nicely… but if you’re kiasu, soak the tank with a solution of a few hundred grams of PP to make sure.
Next, fill up the tank with clean, duly de-chlorinated, tap water. Don’t use any of your old water! (Refer point no. 1)
Put an air-stone in the tank to aerate and circulate the water. (Refer point no 1 again and you should know your old air-stone is a bedding ground with BB in it. Thoroughly clean it, or just buy a new one. Doh.)
Put a few cheap and healthy fishes in it. If you use sick feeder goldfish, the water will turn brown instead! Use good cheap and healthy fish only!
Turn on the lamp for as long as you like. Oh great, we’re stressing the poor fishes again. I am covering up my backside by reminding you, once again, to use your cheap fishes! tongue.gif
Okay you’re ready and all you have to do now is wait patiently. Feed as per normal. Ideally feed with bloodworms, or Hikari Lionhead pellets. Don’t take your chances by feeding pellets containing PSB (such as Chroma.) Observe carefully over the following days. Discard the water if it turns brown. When the water is lightly tinted or you’re somewhat colour blind, green can looks brown. So how? Just find a small all-white ceramic cup and fill it with about 1 inch of your green/brown water in it. The true colour will show up clearly especially when you compare it with another identical cup filled with clear water.
After about 2 weeks you should get intensely green water. Siphon out 10% into a small pail. Discard the rest and start again. This time you should get obvious green within 3 days.
Once you’re satisfied that you can reset your green water reliably, i.e., changing intense green and seeding 10% to restart again and having to repeat it in a week’s time, you can finally put your prized fishes in it.
Er…. hello… no where in my above rumbling did I mention anything about the use of an OHF, canister filter, IOS filter, sump filter, coffee bag filter etc. So… bury your expensive bio-filtration toys in the storeroom if you want to use green water. Why? Refer to point no. 1 again. mad.gif
Oh yeah, read up the various discussions in this board on green water to understand its behaviour as this post merely touches on how to cultivate green water. Using it correctly is beyond its scope.