pH dropping

[Suda Nim]

I'm getting concerned about the pH in my betta tank (5 gallon, planted, gravel and laterite substrate). When I set up the tank and did a fishless cycle, the pH stayed nicely in the 7s (generally around 7.6).

Lately it's been getting pretty acidic, and something happened to my cycle (I'm reading ammonia of up to .5; I do PWC to bring it down to under .25). The pH test only goes down to 6, so I wonder if it might even be lower than that. I tested the fresh tap water today, and it's about 8.2!

I worry about:

Why is the pH even dropping this low?

During a water change, I'm adding (dechloriated with Prime) tap water of a very different pH. Am I shocking the fish with the pH change?

My mystery snail recently died. I wonder if the low pH contributed.

photo: tank water on left, two days after 20% WC. Right shows tap water.

[BigPoppa]

Im in the process of cycling 2 tanks right now and my Ph has jumped all over.

Im told this is normal during the cycling process.

[Tiari]

If your PH goes too low, your cycle will stall out. Its not dead exactly, it just no longer functions. Since your PH is low, and is likely very low, your rising ammonia is due to a stall.

Things to try:
Clean substrate really well, and rinse the filters.
Try a partial small water change daily to see if it raises the PH

If the PH continues to stay low, you can get crushed coral and place a bit in a filter bag in the filter. This will raise the ph, and you can check the level and add more if it isn't high enough. This will stabilize the PH.

I have this same issue, and regardless of water changes or cleanliness, the PH crashes and the cycle stalls without crushed coral constantly in the filters. I have never determined what precisely is the cause, however, and have stopped searching for an answer as it is very frustrating. The coral does work, and keeps things constant and consistent.

[Suda Nim]

Thanks, Tiari. I'll get some coral tomorrow.

I have some cuttlebone on hand. Is there anything I can do with that?

[Cermet]

You might want to get a kit to measure your GH and KH. Your water sounds very soft. The idea for coral is a good one.

[Suda Nim]

I don't have a liquid test, but the dipstick says kH 80, gH 75.

[Cermet]

If memory serves, those mean your water is rather soft. pH swings will occur; the tank pH will change with time.

[Suda Nim]

Wow - soft water in Texas! Maybe I can bring in a lump of limestone from the yard... J/K.

[Suda Nim]

I added coral today, and did a 20% WC. pH is 6.8. We'll see how it looks Monday.

[Suda Nim]

Okay, that worked a little TOO well. Here's the pH two days after adding coral to the filter:

8.8! I should use it for raising cichlids or cleaning my drains! After I saw this, I took out all but about 1 tsp. of the coral.