help with p.h. please

[KevyMv]

My ninety gallon been running for about 2weeks. I've done a couple (10 gallons total) small water changes. Most of the water I took from the person who had the tank before. I have a shrimp, Koran angel (only new fish, the rest came with the tank including live rock), Clown, couple of snails and a starfish. All the water is testing perfect except the P.H. which used to be 8.4 last week but now is at 7.4. I was planing on doing a 10 gallon water change tomorrow what do you guys think. Also I have a skimmer and 25 gallon sump underneath.

 

[lando]

So this is an established tank that has been moved? Ph is a bit low. However, it is not going to harm the livestock as much as a rapid change in Ph. Bringing your Ph up slowly is critical. It will take several days to increase it back to 8.0-8.2. One point every other day is a good goal to shot for. For now, try removing the glass tops on your tank (if you have them and your lighting until allows) and agitating the surface of the water with a powerhead. This will increase gas exchange and should raise Ph.