This does not make much sense...

[save_goldie]

I introduced myself a few days ago. I work for my aunt and uncle in their pet shop. The aquatic department is small. We sell a variety of freshwater fish from 6) 29 gallon, 10) 30 gallon breeder and 8) 20 gallon longs. We plan to remove two 20 longs and replace them with 30 breeders, making each column of tanks uniform, a 29, two 30's and a 20 on top.
We also sell goldfish from three 38 gallon tanks. The goldfish all have AquaClear 70 power filters. The 29's and 30's have AquaClear 30's and the 20's have AquaClear 20's. Some of these are older, but the same, just called AquaClear 150 or Mini.
Anyhow, here's the problem. We try to keep our water's pH around 7.0. Most of the year, it comes out of the tap around 7.0. In the winter, more like 7.2. Most, but not all tanks have drifted down to a pH of 6.4. Some are only 6.8, which is OK, for the most part. Our water is very soft, around 2-3 degrees KH.
This might be part of the problem.
I do a water change of 10% every week on every tank with a gravel vac. We have about 1/2" of gravel in all the tanks. Generally 1-2 plastic plants in each tank too. We don't sell a lot of live plants. We do have some kept in separate tanks. I can proudly say Ammonia is 0ppm in all tanks. Nitrite is 0ppm in all tanks. Nitrate is 0-5 (maybe 10 in a rare case) ppm.
So I've increased water changes to every 4-5 days. I did all the "problem tanks" a 20% change tonight after we closed. Those closer to 7.0 only a 10% change. Every tank is still reading the same. I can change 20% of the 6.4 with 7.2, I'd expect to see a small increase when testing some 30 minutes later, but I am not. I will do more changes Tuesday or Wednesday.
My uncle says "put in a dose of Proper pH 7.0 and be done with it." We sell about 3-4 jars of it every week. We sell 1-2 jars of Proper pH 8.2 every week. We sell about 1-2 jars a month of 6.5 and 7.5...
Personally, I don't want to use it. Never have here. Never at home. I would like to get some of these numbers up however.
Any ideas of natural remedies?
Thanks.

[fishboy]

seashells or other calcium sources such as cuttlebone are a natural way to raise hardness and pH. Just pop them into the tank or(as i like to do) into the filters' media holders

[sambi7878]

I agree with fishboy! As what i always hear, crushed corals is good for raising water hardness.

[ron v]

I think you need to change more water. I would also retest for nitrates. I suspect your test kit is not reading correctly. Nitrates ( nitric acid ) buildup will cause a PH drop. Pick one tank and do a 50% water change every day for three days and see if that takes care of the problem. The Proper PH, PH up and PH down are a waste of time and money. good luck.

[Alin10123]

Check your tap water supply too. Maybe the tap water supply has a different PH.

[ron v]

Originally Posted by Alin10123

Check your tap water supply too. Maybe the tap water supply has a different PH.

He addressed this in his post.