Sensei, when you do the half-and-half thing, does the water STAY at the new (lower) pH, or does it all go back up again after a few days in the tank? Maybe that's something I could try ... it's just about the only thing I haven't tried.
Due to my desire to grow plants that do not do well over pH 7.4, breed Blue Rams, and keep all my community fish happy, I've been trying to lower the pH on my 7.8 tank. Here's what I've tried recently:
1) DIY CO2 with a Pepsi bottle, yeast, hose, etc. Flopped miserably. It bubbled about five times the first evening and then nothing.
2) A Jungle "Fizz Factory." It works really well as far as it goes--over several days, my pH came down to 7.2, but only stayed there as long as I kept adding fizz tablets (I figured out that I'd need to use about 2 tablets a day, and a pack of 16 costs $7). And the large, plastic rectangle that sits inside the tank (CO2 holding tank and reactor--bell type) didn't do much for my tank's looks, either.
3) Sodium Biphosphate. An lfs owner with tapwater at 9.2 swears by this stuff, and says her tanks all hold at ph 7 without adding anything else to her water. I bought some and tried it. It did lower the pH, as long as I kept dosing, but now I've got slightly cloudy water because of suspended, undissolved mineral deposits or something resulting from the action of the Sodium Biphosphate. When I stopped dosing, the pH climbed again. (I called her back to ask about the cloudiness; she recommended I use a "Water Softening Pillow," a day on, a day off, and one more day on after each water change ... Aquarium Pharmaceutical sells both items, but I didn't buy the pillow. I gave up.)
Don't worry, all these changes (from 7.8 to 7.2 and back again) were done very slowly over a period of weeks, and no fish have suffered ill effects from what I can see. But, boy, am I discouraged.
The first time I measured my tank's KH, about a month ago when I began these adventures, I got a reading of 8. I measured it again a few days ago, and it was 12!! Arggghhhhhh.
I've got a 38-gal tank; lugging gallon jugs of distilled water is not an attractive prospect, but I'd do it if it would work. Would it work on a one-time basis, just to get my present tank where I want it? And then all I'd have to do is use whatever method I need on the new tap water for water changes later on?
I do NOT want to lug 7 or 8 gallons of water from the store every two weeks to do partial water changes. And I cannot afford injected CO2. But I do notice a difference in the fish's coloration, among other things, when they're in a pH of 7.2 or so as opposed to 7.8 or 8.0. You can see it especially on the black tetras--the silver/blue strip seems to be more ... er ... rusty looking or something on the blacks who have been in my tank longer. I could definitely see the difference when I put a few new ones in there with them, to bring the school up to nine.
I think the lower pH is good for the fish, although they do "okay" at a higher one. If there's any way to get my tank to 7.0 or thereabouts, I'd be one really happy camper. Does anybody have any suggestions? Sure would appreciate it.
-- Pat
