I tested my pH today and its quite low. It used to be in the 7.0 -7.2 range. Is it a problem? Should I use something to bring it up? I have Proper pH 7.0 and baking soda on hand.

A pH of 6.4 is quite low. You used to have it in the 7.0-7.2 range, correct? Was this the way it was coming out of the tap? Have you tested your KH? WAter that does not have a sufficiant buffer cannot hold a steady pH.

Before you change anything, take a read of your water that you are using in the tank. If you just use Proper pH 7.0 and you lack sufficiant buffer, it will not remain at 7.0 for long. We need to discover the REASON that it has dropped....

Do you have new driftwood or other biological matter in the tank that could be dropping your pH? That is a common cause. Perhaps the makeup of your tap water has changed......

I bet this can be solved for you!!!!

I dont have a KH test kit, only a GH which Im not sure on how to use . The tap water is reading 7.4 -7.6. I dont have any driftwood or anything else I can think of that would cause a pH drop. Theres a 3 inch Moor, 6 inch Dojo and a snail. This is the only tank reading that low, the others are 7.0.
Thanks for your help Daryl

GH will do, too, but SHOOT I cannot find my directions for using the test.....I do not remember what color it turns or the multiplyer 17.9 or something.....

I shall have to try harder for you - or maybe someone else knows....

Sinceyou are MidWest, I am assuming you probably have a Tetra Test GH test kit? That is probably the most common one I see around here......

??????????

ANyone!!!!

I think that I would guess that without the test, you need to add a buffering agent to the tank to stabilize the pH - and then bring it back up - by changing water, etc. until it is where youwant it to be. If you use Baking Soda for buffer, be aware that it will take your pH up all by itself. You could try that - use just a tiny bit and test to see where it gets you.

Kingyo has pointed out that using Baking Soda in the long term perhaps introduces too much sodium to the tank and has suggested calcium carbonates for buffering agents. I have yet to find a reliable source of that - using shells did not keep it steady enough for me. I have been using Baking Soda for a while with no side effects that I can determine, so I am sure thatyou should be fine using it for a while until we determine what is going on. I add the baking soda to RO water at 7.0 and it goes to about 7.6 automatically.

Eventually, what you need to do it test your water and find out if it has any natural buffer in it as it comes from the tap, for a beautiful 7.4 from the tap could plummet without a buffer to stabilize it.

The gh kit I use turns orange after the first drop. Then you add one drop at a time until the solution turns green. Take the total number of drops and multiply by 17.9 too give you a gh reading in ppm(parts per million) or mg./L(milligrams per liter). Same thing.
Unfortunately a GH reading is not going too help much with your ph problems. You need too get a KH reading as I am pretty sure it will be low. One of the preferred methods too increase your kh is the addition of baking soda. Once you increase kh your ph should stabilize but at a higher level.
The reason why your other tanks are at 7.0 and this tank is lower is because Kh is constantly used up thus allowing your ph too sag. It seems like this tank is just using it up faster.

I have no idea how to do that certain test...i have one of those deluxe ph kits....but my ph is ALWAYS low in my tank...has been that way for 2 years........my fish are fine, but i will warn you, snails will not survive very long in a low ph water

Ahh ok, Ill test my GH. I couldnt find a kh test at my LPS so I probably have to order one off the internet.

Grain,
I know the snail wont do well in the low pH. I just moved him there so hopefully he'll be ok until I get the problem figured out.

BTW,
My kits are Aquarium Pharmaceuticals.

Just a thought do you have any ornaments in there that you place recently.

Some of them will cause a ph problem?

Good thinking Koko! I just redid this tank. It was a natural decor(terra cotta pots, river stones, real and fake plants) and now its well....not. There are blue plastic stones, flouroscent green plastic plants, a plastic-ish(?) starfish, a fake plastic-ish(?) white coral, and 3 little plastic jellyfish, and a bubble wall. But I wouldnt think that any of those things would change the pH. They are all made for the aquarium.

My GH is 143.2.

Now that you know that your Gh is fine can you get a KH reading? Kh is also known as total alkalinity and carbonate hardness. It is a simple test that is similar in use too the GH kit. I am surprised the AP kit you have does not test Kh as well.
Kh is an extremely important parameter too know since it is responsible for maintaining your PH. Without knowing your kh more frequent water changes will help with your sagging PH.
If you do test for Kh please test your source water also. This way we can get an idea of what is going on in your tank.

Ill look for a kh test this weekend. My AP kit only had ammonia, nitrites, pH, high range pH, and GH. I bought a separate nitrates kit.

Oh and I forgot but that tank also has a rubberlip pleco.