PH and water changes question

[islandguy11]

Hi, I have an 80 gallon tank with a ~ 6 inch fast growing Red Texas (Texas X Flowerhorn cross). When my water comes out of the tap (non-chlorinated well water here in Thailand), the PH is about 7.2 due to CO2 in pump system -- I don't yet have anything to test KH/GH, lfs will have in a couple of days.

Anyway within an hour or 2 max after going into the tank (after ~30% water change) the tanks PH shoots right back up to it's normal 8.5/8.7 -- which I also got the exact same results from a tap water sample in a small bucket with air stone for 1.5 hr. In the tank I have no crushed coral or anything like that which would raise the PH.

Setting aside/getting CO2 out of ~25 gallons before each water change really isn't a workable option for me.

So my questions are: a) how bad for my fish is that temporary PH difference for an hour or two? and b) is 8.5/8.7 OK or too high for optimal growth/coloration of my Red Texas? Thx in advance for any advice.

 

[tlindsey]

Hi, I have an 80 gallon tank with a ~ 6 inch fast growing Red Texas (Texas X Flowerhorn cross). When my water comes out of the tap (non-chlorinated well water here in Thailand), the PH is about 7.2 due to CO2 in pump system -- I don't yet have anything to test KH/GH, lfs will have in a couple of days.

Anyway within an hour or 2 max after going into the tank (after ~30% water change) the tanks PH shoots right back up to it's normal 8.5/8.7 -- which I also got the exact same results from a tap water sample in a small bucket with air stone for 1.5 hr. In the tank I have no crushed coral or anything like that which would raise the PH.

Setting aside/getting CO2 out of ~25 gallons before each water change really isn't a workable option for me.

So my questions are: a) how bad for my fish is that temporary PH difference for an hour or two? and b) is 8.5/8.7 OK or too high for optimal growth/coloration of my Red Texas? Thx in advance for any advice.

Drstrangelove

 

[Drstrangelove]

So my questions are: a) how bad for my fish is that temporary PH difference for an hour or two? and b) is 8.5/8.7 OK or too high for optimal growth/coloration of my Red Texas? Thx in advance for any advice.

1) Many species have been tested for the effect of rapid and large pH changes within a range of ~5.0 to 9.5. Little or no effect has been noted. (By rapid, in some cases I mean placing a fish accustomed to one level into another tank at a completely different level with no adjustment period.) In the range of 7.2 to 8.7, based on studies I've seen, the fish would be fine. I would expect that it's common for some people doing very large water changes to have large pH swings.

2) I haven't seen any studies on growth and pH over any long term period. My guess is there will be no effect, but that guess is based on the observation that numerous species can acclimate in ranges as wide as 5.0 - 10.0. The drawback of a 8.7 pH is that ammonia and certain metals are more toxic at high pH, so it's possible that it would have an indirect effect. But in otherwise pristine water, I wouldn't expect a problem.

3) As for coloration, I haven't kept this species and have no idea what impacts coloration.

 

[islandguy11]

1) Many species have been tested for the effect of rapid and large pH changes within a range of ~5.0 to 9.5. Little or no effect has been noted. (By rapid, in some cases I mean placing a fish accustomed to one level into another tank at a completely different level with no adjustment period.) In the range of 7.2 to 8.7, based on studies I've seen, the fish would be fine. I would expect that it's common for some people doing very large water changes to have large pH swings.

2) I haven't seen any studies on growth and pH over any long term period. My guess is there will be no effect, but that guess is based on the observation that numerous species can acclimate in ranges as wide as 5.0 - 10.0. The drawback of a 8.7 pH is that ammonia and certain metals are more toxic at high pH, so it's possible that it would have an indirect effect. But in otherwise pristine water, I wouldn't expect a problem.

3) As for coloration, I haven't kept this species and have no idea what impacts coloration.

Thanks so much for your reply Drstranglove, great info and also puts my mind at ease. Will watch the ammonia levels as usual, and maybe add some more driftwood to possibly lower that PH a bit over time.