Thanks for the info Mike. Just a couple of questions. Black worms? is this an American delicacy or is it another name for Tubifex and are you sure about the pH 4.8 - 6.0 sounds a bit low especially as the majority of my fish are breeding and rearing young in 6.5. I've checked into R/O units and I've been informed that, because of the water pressure, temperature and levels of other stuff in the water (KH 9.0 deg, pH 8.0 and 650 micro-siemens) I need a 24gal per day unit, which will give me between 15-18 gals. The only problem is the cost, I don't know how much you pay but the lowest price I've found is $250 and that's just the pre filter and membrane pod the next closest was $350 which included auto-shut off and various other valves and lines. I bow to everyone's experience with these units but just to breed "Checkerboards" I wonder if the outlay will be worth the income. Comments on fry growth rates with and without these units would be welcome along with any other comparisons. PS I've dropped the idea of distilled water it works out more expensive than the R/O unit Stuart Greenley Kingston upon Hull, England stuart@snoopers.karoo.co.uk - ----------