Why won't the ph in my fish tank go up?

Question

I've tried using "pH up" drops from the pet store to no avail. I've waited a couple days and it won't go up. It's currently around 6.6 and alkalinity around 80. Nitrate/Nitrite/Hardness are always safe. I always have this problem when I clean the tank.

I keep about 10% of the old water in the tank because it's usually so gross by the time I clean it. But I'm afraid to clean it often because of the pH problem. I use drinking water because tap water was always too hard for them (even with conditioner), and the apartment is around 78-80 degrees during the day. Is it the water, temp or the combination? I can't figure this out and I don't want my fish to die!! Please help!!!

Answer 1

First off, if you're doing 90% water changes as you imply, quit doing that. Do smaller changes of about 10-20% a week.

Also, when was the last time you vacuumed your substrate? Decaying food and waste in the gravel can lower pH as well. Vacuuming it could help, especially if the gravel is deep (more than an inch or two).

If you need to up the pH, add a little bit of baking soda to the water, or go to your local fish store and buy a small amount of crushed coral or aragonite (calcium carbonate). If you place this in a small mesh bag, the mineral will dissolve in low pH situations, help buffering the water.

Regardless of the method, only raise your pH slowly. If the fish have too wild of a swing, they can  go into shock.

Answer 2

What kind of fish are they? Your tap water has chlorine in it that's why it kills your fish. They make a water conditioner that gets rid of it, and makes it safe, or if you don't want to do that, you can let the water set for twenty four hours and it will be safe.

Answer 3

Ugh don't use that Ph up stuff...add a chunk of limestone to your filter and after awhile your pH will go up

Answer 4

If you want your pH to go up, try adding a few Calcium Carbonate (limestone) rocks.  They will help your pH go up.  Here is a nice article on carbaceous rocks: http://freshaquarium.about.com/cs/qa/f/f...

And here is a good website for buying limestone:  http://cgi.ebay.com/Holey-Rock-Large-Lim...

Although I recommend buying one at a local pet shop so you don't have to pay shipping and handling.  Rocks are heavy, and expensive to ship.  

You can also used crushed coral, you have any around.  Just crush some limestone or coral and replace a bit of your gravel with it.  Your pH will be buffered upward.

Don't mess too much with the pH since rapid changes in pH can shock and kill fish.  Those calcium carbonate rocks will very gradually change pH and be safe for your fish.

Answer 5

Just stop messing with the pH, 6.6 is fine for most fish.

If it's between 6 and 8 and stable.. leave it alone.

If your tap water is very hard it will be also high pH, it's possible the sudden change in pH, hardenss and temp is shocking your fish and killing them when you do a 90% water change.

You could try just changing 20% of the water, every few days so there is no sudden change. Use a water treatment like Prime in case you have a chlorine problem.

Another option would be to mix your bottled water with tap water. That will give you a pH and hardness somewhere in the middle, but avoid doing any huge sudden change and again shocking your fish.

Try and match the temp of the new water and tank water, a little bit from the hot tap is OK, just enough to match the temp.

Also when you say the water is Yuck... do you mean it's gone green? Thats an algae bloom, harmless, but ugly. Reduce the amount of light your tank gets to reduce the algae growth. Then you wont have to do huge water changes, and therefore less stress on your fish. 90% water change aren't dangerous in themselves, unless you are changing the water parameters too much. But if your tank is running properly then 20-30% per week changes should be fine.

Ian