How to raise fishtank PH?
October 5, 2005 6:00 AM   Subscribe

Another fish question: what cheap chemical can I add to my tank to raise the PH? Its a big tank, and those little bottles from Petland are getting expensive.
posted by StickyCarpet to Pets & Animals (14 answers total) 1 user marked this as a favorite
Baking soda
posted by deshead at 6:12 AM on October 5, 2005

And here're lots of details about water chemistry
posted by deshead at 6:17 AM on October 5, 2005

Wow, that just seems too obvious. And for those needing to lower the PH? What, vinegar?
posted by StickyCarpet at 6:18 AM on October 5, 2005

Vinegar has too much organic material in it. That could feed algae growth.
posted by Pollomacho at 6:59 AM on October 5, 2005

Oh, and a good way to keep a more constant ph and raise the ph at the same time is to add some sea shells, limestone rocks, chunks of marble (or a marble statue even) or some little pieces of coral to the tank. This raises the hardness of the water too, which can help with ph stability.
posted by Pollomacho at 7:06 AM on October 5, 2005

Just be careful and make sure those shells have NEVER been bleached! The bleach can leach into the tank and kill your fish.
posted by agregoli at 7:30 AM on October 5, 2005

The thing about baking soda is that it doesn't last, and it can cause your pH to spike up and then drop off. That's really hard on your fish. I have ridiculously soft water. (It tests at about 5.5 out of the tap.) The LFS folks kindly sold me all sorts of Equilibrium, Acid Buffer and Alkaline Buffer products, but I found they left the water cloudy, and they needed constant testing and fiddling with.

So I did some searching around online and came across this post on Aquaria Central (which is a great resource for all aquaria-related questions). So I went back to my LFS and bought a bag of crushed coral, put a few teaspoons in the toe of a nylon, tied a knot in it, and dropped in into the filter. My pH has been nice and stable at 7.2 ever since.
posted by ambrosia at 7:58 AM on October 5, 2005

A cheaper source of all kinds of aquarium supplies is Drs. Foster & Smith. Their catalog also includes a lot of basic aquarist information (with plugs for products they sell, of course).
posted by Kirth Gerson at 8:03 AM on October 5, 2005

I have to make a correction: I put three Tablespoons in, not three teaspoons. Sorry about that. A bag of crushed coral is pretty cheap and entirely fish-friendly.

In addition to the good Doctors F&S, an even cheaper online source for aquarium supplies is Big Al's.
posted by ambrosia at 9:24 AM on October 5, 2005

For most freshwater fish pH is a non-issue. It's expensive to adjust with chemicals and difficult to keep adjusted if you're doing water changes like you should. There are more important things to worry about, like frequent water changes and a good variety in their diet.

Change is bad. Fish better adjust to an "incorrect" pH than one that is constantly in flux.

If you have a saltwater tank or freshwater plant aquarium, just ignore me.
posted by mealy-mouthed at 9:34 AM on October 5, 2005

I'll 2nd the crushed coral idea, but I'd add that it's a good idea to rinse it first, or maybe boil it, and then let it sit in a bucket of water overnight before adding it to the tank. This is actually a good idea for just about anything natural that you are going to put in your tank.
posted by darkness at 10:23 AM on October 5, 2005

pH is a non-issue until... At about 5.5 your biofilter quits; the good news is that the resultant ammonia build-up is essentially non-toxic at 5.5. The bad news is that when you do a water change (or even a large top-off from evaporation) with tap water at a higher pH, all of that ammonia is now in a much more toxic form...

But it is absolutely correct that keeping it stable is important; biofiltration lowers pH as a bi-product, so the essential thing is to establish an alkalinity buffer that will hold the pH stable.

Assuming that your fish can tolerate around 7.4 - 7.6 (most freshwater fish handle it fine; some really sensitive ones from acidic waters maybe not), the easiest way to deal with all of this is to include some calcium carbonate buffering material in the tank, as Pollomacho suggested.

If you're worried about contaminants, a pound or two of (well-rinsed) crushed coral gravel (sold for marine tanks usually) as ambrosia suggested can be had from most pet stores pretty cheap (especially since it's a one-time purchase.)

It will very slowly dissolve into your water as your biofilter produces acid, and maintain enough alkalinity to hold your pH at around 7.4 - 7.6.
posted by nonliteral at 11:02 AM on October 5, 2005

I use a tap water conditioner that removes chlorine (breaks the chlorine bond) and detoxifies heavy metals. One drop per gallon does it. Seems to work OK. Anyone know what this chemical is? Does it change the pH?
posted by weapons-grade pandemonium at 3:13 PM on October 5, 2005

PH for me is not a non-issue. I have several dead fish to prove.

I have a 150 gallon tank with fluval charcoal filter pumps.
I found I could tell from their behavior when the PH was out of range: they would show little action towards the food dropping in front of their faces. Not like they aren't hungry but like they are incapacitated.

They also begin to "pace" the bottom edge of the tank, like they are looking for a way out.

Both theses behaviors stop almost immediately when I reset the PH.

This last time I let it go too far out (off the scale on my PH tester) and one got a sore on its side (a 5 inch red-eyed foil.) Once I noticed that I resolved to pick up the PH chemical the next day. Too late, three dead fish by morning.

Retting the PH took 4 of those $5 bottles from petland, hence my question.

If baking soda spikes too much, couldn't I just put a pinch
in every day?
posted by StickyCarpet at 8:01 AM on October 9, 2005

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