PH stuff

[72gallon]

I have been having problems with getting my PH over 8.0. Here are my specs:
- 72 gallon tank - 4 months old
- PH 8.0
- Amon/Nitrite/Nitrate 0
- Salt 1.0225
- Temp 78
- 130 watt light
- 2 power heads
- protein skimmer
- 404 canister filter
- 40 lbs live rock (I add 10 lbs every month)
- 5 gallon water change ever week
I have been adding PH buffer and I see it jump to 8.2 then slowly fall back to 8.0. What gives?
Also, when I do a water change I prepare the water as follows(this was the advice of my local pet shop)
- 5 scoops of Instant Ocean
- Add water (5 gallons) @ 80 degrees
- Add Prime - removes bad stuff from water
- Add power head
- Generally in an hour the salt is mixed up and the readings are 1.0225 salt before I add it to the tank.

 

[beaslbob]

Daytime ph drops are caused by increased carbon dioxide.
My ph dropped to 7.4 and lower until I added plant life in the form of macros algaes to my display. It rose to 8.2-8.4 in a week and has stayed there for over a year. All using untreated tap water, no water changes, and no additives of any kind. So it was the action of the added plant life and nothing else.
I recommend you add plant life to your system or at least let the existing plant life (even the ugly algaes) thrive.
I also to not recommend or use any water conditioning (aditives or filters) of any kind. RO/DI for instance removes buffering that helps maintain ph in our tanks.

 

[reefnut]

What is your alkalinity & calcium levels? Good surface movement will do more than a few plants.

 

[72gallon]

ReefNut
I have no idea what my alkalinity & calcium levels are. I don't have any test for these. Is the way I do water changes correct? I don't let the water sit for 24 hours like most...Only for around an hour or so. The Prime is supposed to remove all the bad stuff from the water.
Also, I have one of my power heads at the top of my tank to disturb the surface water.

 

[reefnut]

When you add a PH buffer you add alkalinity. Adding alk with out adding calcium will cause a imbalance in the water chemistry. If you do not want to test stick with the water changes and skip the buffing.
What time of the day are you testing the PH?

 

[72gallon]

ReefNut
I test the PH in the evening ~7pm

 

[reefnut]

A PH of 8.0 is not really bad. Test the PH right before lights on and at lights off. These two readings will give you the high and low. As long as it doesn't drop a lot during the night IMO your fine.
I think some added circulation would probably help. Adding a refug with macro algae will help level the PH swing if you run the refug lights opposite of the display...

 

[72gallon]

What are refug lights? Is 2 power heads not enough for water movement? Thanks for all your help...if PH is OK at 8.0 then I am just going to leave it that way.

 

[reefnut]

A refugium is usually a separate tank that holds macro algae, sand rocks etc... that is hooked in to your main tank. Do a search and you'll find all kinds of info.
What "gallons per hour" (gph) are the power heads? The canister is rated at 340gph... that added to the gph of the power heads would be your total gph. In a 72g tank I would suggest having no less than 720gph... that is 10x turnover as a minimum.
added: you can add in the skimmer also if it is a hang on skimmer.