Water Changes

[karaim]

I have a question regarding water changes. I have been doing water changes (about 5% once a week) for 2 months. However, I think I overlooked one thing: the PH.

The PH in my tank is 8.4. The PH in my replacement salt water is 8.0. Won't such a decrepency be detrimental to the fish? Should I artificially raise the PH in my replacement water? But if I do that, won't the total PH in my system go up as well since the PH in my tank is probably increased by the Live Rock and Sand Bed?

 

[GShorty1981]

not on 5% a week,its like a drop in the ocean.

 

[Colin_T]

5% water changes don't do anything for a tank. It is too small to dilute any build up of nitrate or phosphate, and is too small to affect the PH or replace any minerals that are being used. Unless you are adding supplements like calcium, and have nitrate and phosphate absorbing granules, you would be better of doing a bigger water change, perhaps 20%.

 

[karaim]

5% water changes don't do anything for a tank. It is too small to dilute any build up of nitrate or phosphate, and is too small to affect the PH or replace any minerals that are being used. Unless you are adding supplements like calcium, and have nitrate and phosphate absorbing granules, you would be better of doing a bigger water change, perhaps 20%.

Glen thanks - good to know it won't make a big difference.

Colin, I will probably do larger water changes, or maybe 5 or 10% twice a week. But the larger the water changes get, won't the PH difference between my water and the new water be detrimental to the fish?

 

[Colin_T]

Doing bigger water changes will affect the PH, therefore you should buffer the new water before you add it to the tank. Most brands of marine salt should have sufficient buffers in them to raise the PH to about 8.5. If yours isn't then perhaps try another brand or just add a couple of teaspoons of sodium bicarbonate to the new water when you make it up. Also you should mix the new water for 24 hours before adding it to the tank. If it doesn't get enough time for all the salts to dissolve you could be getting a false reading because of the undissolved minerals.