The Puffer Forum

RTR wrote:There is no downside to large-scale water changes provided that the tank and replacement water parameters are comparable. If they are not comparable, osmotic shock is always possible. Flow-through tanks in public aquaria frequently get more than that level of changes daily, as do some commercial and private breeding tanks.

HTH

I've tested my tank water, and my tap water, and the only difference is the nitrates in the tank before a water change. The highest my nitrates get is to 10, ever. Yet if I change more than 70% of my water at a time I go through a mini cycle. What exactly in the tap water could be causing this do you think?

Ditto the slime mold. Mine was white and was in one of my breeder tanks. If it continues you have a most likely water quality issue. More frequent partials and a good substrate vac weekly will help keep it under control / eradicate it.

If your cycle bacteria are being knocked down by large-scale partials, either the temperature is way off, or more likely, your dechlorinator/dechloraminator is not appropriate or is incorrectly used.

I use prime. Its pretty basic and I find it hard to dose incorrectly. The tap water I use just comes out and I do nothing more than a feel test for temperature, so maybe but im sure im not that far off, I havent been cleaning the inside of my glass like I used too, so its very slimy, I dont get algae anymore, atleast not on my glass like before so maybe that awesome slime found its edible organic matter on some accumulation of aquarium slime, and maybe microscopic debris that got caught there...from what ive read on this mould slime, it needs a food source, and that source was on a patch of glass..if I get it again I will test my water while its in there to double check. I kind of miss it now it was cool looking.

Don't kid yourself - the biggest difference in tank water vs. tap water is organics, a.k.a DOC, dissolved organic compounds, which we cannot measure with test kits. What you do not know can hurt your tank. DOCs are assumed to be roughly proportional to nitrate in unplanted tanks, but whether smaller, equal, or greater than nitrate is unknown.

The unknown scares me, that's why I do more than required to keep water quality up