Low pH?

[Karackle]

I was doing my bi-weekly water change on my well established 20g tank and decided it had been a while since I did water parameter checks so i figured I'd do them. The ammonia, nitrIte and nitrAte were all normal (0, 0, 10-15) but the pH was unusually low, it was 6.0. I never recalled my pH being that low, but since memories can lie to us, i figured i'd check some other things. So I checked my 5g tank, pH there was ~6.8, and the water coming out of my tap is 7.8+ (my drops only read to 7.8, the water was blue which is over 7.8 but who's to say how much.)

So my question is threefold:

1) What causes the pH to drop?

2) Should I worry about it / do something to try and bring it back up?

3) Could the low pH have caused the problem with intestinal parasites I recently had?

Thanks in advance!!!

Tank Parameters:
20g High, low tech tank
regular aquarium gravel, 78 degrees, Penguin Biowheel 100 filter
Flora:
Purple Cabomba, Wisteria, Cryptocoryne wendtii red (small), Crypt wendtii green (large), Crypt spiralis, Anubias (nana i think)
Fauna:
3 female Bettas, 3 mollies, 3 neon tetras, 3 glolight tetras, 3 zebra danios, 1 female guppy, 1 clown pleco

5.5 Gallon, low tech
regular aquarium gravel, 80 degrees, Red Sea nano filter
Flora:
Purple cabomba, wisteria, Crypt wendtii Red (large and small), crypt w. green, anubias (again, nana i think).
Fauna:1 male betta, 2 otos

[Buckeye_Robert]

Hi
Can you get a KH reading
any added wood in the tank?

[Karackle]

I don't have a test for kH, I added some wood a while ago, but this is the first time I've noticed a drop in pH since then, though i don't test it weekly or anything, so I suppose it could have been the wood. It's malaysian driftwood (if i recall correctly )

[Karackle]

Should I do anything other than water changes to raise the pH or should I leave it as is?

[lauraleellbp]

I'd just do regular water changes, and not worry over much about your pH. As long as it doesn't drift too far from your tap water you should be OK and regular PWC are all you need to do to prevent this.

[Karackle]

Sounds good, that's what i figured but I thought i'd double check! As always thanks so much fot the helpful advice!!!