Raise PH & Lower Hardness??

[catcha]

Dying Fish. Please help.

I have had a 46 gallon freshwater tank for many years. I thought I had the hang of it. Recently my fish have started dropping like flies, about one dying a week (including my 6" Angel who was one of my tank's very first inhabitants). There aren't any signs of disease, and my nitrate, nitrite & ammonia levels are all perfect. Doing water changes seems to accelerate the death toll. I did move to a different part of the city over 6 months ago, and the water here has a PH of around 6.0, and a total hardness (GH) of over 300 ppm, and an alkalinity (KH) of 20 ppm. I know these levels are not ideal, but they have been constant. Could the PH & hardness be the culprits after all this time? Any ideas?

Is it possible to raise the PH and lower the hardness? From what I have learned, these two go hand in hand, and it seems that my water is odd, since both of these levels are pretty much off the charts in opposite directions.

 

[jsoong]

Hi and welcome to AA.

That is certainly weird water you have. The pH goes with the KH, so that part makes sense. GH & KH usually go hand in hand, but not always. A solution of MgSO4, CaCl2, or something like that would give you high GH, low KH & low pH. The problem is we don't know what is actually in the water. Perhaps you can dig up a water report from your water co to see what is actually in it.

If all the parameters are stable, however, the strange levels are not likely to cause fish death. It would be useful to compare the levels in the tank vs tap water to see if there is any drift ... esp. the pH, low KH might give you unstable pH that is stressing the fish. And if the tap parameters are very different from the tank's, doing pwc's might cause problems.

There isn't an easy way to increase the pH while decreasing the GH. Adding NaHCO3 (baking soda) will increase the pH & KH, while leaving the GH unchanged. If you want to lower the GH, you pretty much have to go with a reverse osmosis unit, stripe out everything from the water, then add back a neutral buffer to get the proper GH, KH & pH.

 

[BigJim]

This may be a stupid question, but do you use Prime or another dechlorinator or do you age the water and let the chlorine evaporate?

You may have moved from a place with chlorine in the water to a place with chloramine in the water. Chlorine will evaporate. Chloramine won't.

 

[catcha]

jsoong, Thanks for the good advice. I wanted to begin adding baking soda over time, but worried about what it would do to the GH.

BigJim, Not a stupid question at all. I use a dechlorinator, but we were also sort of wondering if it could be suspect. I plan to buy another bottle next water change and see if that makes any difference.

Would diluting my water with distilled water lower the GH, if I did it at a slow enough rate that the low oxygen levels wouldn't be a factor of course?

 

[jsoong]

Well, yes, you can dilute out the GH with distilled water. <That is basically what R/O water is.>

For the best control, you would use pure distilled (or R/O or D/I) water & mix in the exact buffers & salts you want. That is how the SW people run their tanks. Some in FW would use tap + R/O as a cheaper alternative. For eg. you might want to mix up 50% R/O + 50% tap + NaHCO3 as your tank water. When you are doctoring your water like that, you don't do that in the tank. You would have a separate container where the water is prepared ahead of time for use. <Aerated, temp matched, etc. prob a day in advance.> <And do switch your tank over to the new water slowly, generally maybe 10% per week.>

However, that is a lot of work to doctor your water just for the GH. GH of 300 isn't that high, assuming that there isn't high sodium or other stuff in the water. Most fish should be able to adapt to that. It might just be simpler to just add baking soda to bolster the KH for pH stability & leave it at that.

This is a good summary of what we are talking about:
Beginner FAQ: Water Chemistry