Constant Ph Bottoming Out

[180gallons]

My ph has been constantly hitting 6.0 even after adding perfect ph.I have recently added some Texas Holy Rock but that is not helping either.I am running a wetdry,fluidized bed filter,and a magnum 350 on my 150gal. setup.I am also using pool filter sand for substrate about 3-4 inches deep.My tankmates are1) arrowana(1) florida gar(1) tiger shovlenose(3) palmas eels.Any advise?

 

[fishdance]

From your post I am unsure whether you want a high pH or a low pH. Whats wrong with 6.0? If you want above 7.0 pH then add some dead coral chunks or rubble. Either in your wet/dry or in the substrate. It will buffer pH and hardness since it is carbonate hardness. No need to monitor pH or add any more additives again.

 

[180gallons]

Iwas trying to keep my ph around 7.0.Is that to high?

 

[DiXoN]

whats the ph of the water out the tank.
whats your water hardness
whats your water change schedule.
i had this issue previously and my water was 7.2 out of the tap, it changed to around 6.0 within 1 week and i was doing 50% water changes every week which was actually hurting the fish.
i checked my hardness and had no buffering and had to add some crushed mussell shell to my filters to help buffer the water and this worked.