How to raise PH value?

[JeffL]

Bro I suggest you invest in a more efficient protein skimmer... got a feeling you have too much things rotting/decaying in your tank... so no matter how much water you change... your NO3 will still remain high 

erm i just change from a lousy jebo to weipro 2011 only last mth, cuz jebo always jam and water leaks....

hmm i cleaned my canister well that day, emptied most coral chips, bio balls and ceremic rings to only a few in one tray...i remember cleaning lots of mince meat noodle soup look alike

the rest is just sponge and rowa

[jervismun]

Rotting/decaying can also be things/nutrients that are not visible to our eyes for example urine/discharge from fishes and corals... these things create Nitrate in the end... so a lot of us rely on efficient skimmers to remove them once they were discharges/released into the water. We will not let it turn into Ammonia --> Nitrite --> Nitrate. So with a inefficient skimmer, all your wastes will have to go through the full cycle therefore in the end... Nitrate factory. Water change can only help that much... really.

For example:

100% tank water = 60 NO3

After 10% change of water (that is if you are using RO/DI water):

90% old tank water = 54 NO3

If you are using tap water (known to have traces of NO3):

90% old tank water = 57 - 58 NO3

So in the end... you are just wasting salt (so to speak).