Tap water ph 8.8, tank ph 6.6 -- ???

I moved to a new city and started up my 85 gallon discus tank 8 months ago. Ph out of the tap in St. Louis is 8.8-9.0!! None of the LFS sell discus here because the water is too hard and alkaline. However, after setting up my tank, aging it, and putting in some "starter" fish (went with Cardinal tetras as a test), the Ph in my tank went to 6.4-6.6, and has stayed there. I have two large driftwoods in my tank, but they are 8 years old and I don't think emitting any tannins. I do not know why my Ph dropped to what discus love, other than good luck. I purchased some discus online, and they are doing so well that two of them paired off and have been mating. I want to start a second tank to breed discus, but I do not know what I did to reach such a low Ph, and am afraid I'll kill off my discus (and anything other than African cichlids). Anybody know how 8.8 Ph out of the tap dropped to 6.6 without any action on my part? Or how best to get there if luck doesn't strike twice?

That's a big swing ! I would be very careful to do big water changes in your main tank.

What I suggest is take some water from your tap into a bucket aerate the water overnight or longer and test the ph in that water. Atleast we will find out if its your wood that's causing the low ph.

How often and how much water do you change? What is your GH and KH? What is your stocking level? How old is your test kit? Do you have substrate? What is it? What is your tap pH after aging (with an air stone) for 24h?

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Originally Posted by Ken K.

I moved to a new city and started up my 85 gallon discus tank 8 months ago. Ph out of the tap in St. Louis is 8.8-9.0!! None of the LFS sell discus here because the water is too hard and alkaline. However, after setting up my tank, aging it, and putting in some "starter" fish (went with Cardinal tetras as a test), the Ph in my tank went to 6.4-6.6, and has stayed there. I have two large driftwoods in my tank, but they are 8 years old and I don't think emitting any tannins. I do not know why my Ph dropped to what discus love, other than good luck. I purchased some discus online, and they are doing so well that two of them paired off and have been mating. I want to start a second tank to breed discus, but I do not know what I did to reach such a low Ph, and am afraid I'll kill off my discus (and anything other than African cichlids). Anybody know how 8.8 Ph out of the tap dropped to 6.6 without any action on my part? Or how best to get there if luck doesn't strike twice?

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Hello, I am in the Kansas City area and our water is nearly identical. I wouldn't worry too much about the drop in Ph as long as it is stable at 6.6. Although my Ph during summer is a bit lower than yours out of tap, it is the same as yours in the winter and my fish grow out just fine... Up until recently, I was traveling up to 4 days per week. My fish were fed lightly with an auto feeder and no one was around to do water changes. My ph was fine and my discus grew out very nice!

With this swing in Ph, I would recommend aging your water before doing water changes.

As far as breeding discus, you will be using RO water which is unstable, but again, regular water changes with aged RO water will help avoid Ph crashes...

Brian

Agree it would be useful to know GH (and/or conductivity) and KH of your tapwater, pH after ageing and also NO3 in your tank

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Originally Posted by Paul Sabucchi

Agree it would be useful to know GH (and/or conductivity) and KH of your tapwater, pH after ageing and also NO3 in your tank

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I used to know these things but it's been a long time since I tested. For peace of mind, I would recommend Ken buy a test kit but not panic in the mean time. I just became comfortable with the water in my area and it's very stable once it ages. The water in St. Louis is nearly identical to the water in Kansas City.