ph level

Question
Hi Jennifer, My question is - I have a 65 gallon saltwater tank the ph is reading 8.8 I am a little confused some tell me that is ok but I am very questionable about it.  My tanks ph usually runs about 7.8.  My fish seem stressed.  What should I do?

Answer
Hi Roxane. A pH reading of 8.8 is not okay in a saltwater tank. The ideal range for your pH to fall in is 7.8 to 8.3. First of all do you have allot of algae weather it be micro or macro algae growing in your tank? Usually the pH in a saltwater tank takes care of itself and very rarely needs to be adjusted. One reason for an excessively high pH to occur in a saltwater tank is the vigorous uptake of CO2 by algal photosynthesis. When this occurs it means that it is time to harvest a good amount of the algal crop. If this is the cause then you should notice a sudden drop in pH after a few hours of the lights being off or when some of the algae is removed. Systems with inadequate biological filtration may face another problem. The percentage of free ammonia rises as pH increases. If ammonia is present in the water the increase of ammonia with the pH rise can cause additional stress on the fish. This may be why your fish are experiencing signs of stress due to the rise in pH. Addition of CO2 will lower the pH as well. If after the lights go out and you test your pH during the period of darkness and it doesn't go down you may want to do a partial water change using distilled water as your mix up water. Keep the salinity a little on the lower side since the addition of the salt will raise the pH as well. Try lowering the salinity only a few points in the water you will be using for your partial. I can almost bet though that when you test your water after the lights have been out for a while you will se a decrease in pH!