Ph, Mh Lighting, And Macro

[Donya]

Since adding MH lighting to my 12g, my macro is growing like mad (what I wanted, since my Turbo eats it) and the pH is going up...pH started out kind of low at around 8.00-8.10 before the MH, but today it was 8.45. It's been slowly rising by about 0.05 every 1-2 days, and isn't going down much at night. I measured it at 8.30 once before lights off, and then the next morning before the lights went on it was around 8.25, so the downward shift is not much.

Since the pH shifting correlates with lights on/off, I am I correct in assuming that the macro & other algae are the cause? Also, if that is the case, can I expect it to level off close to where it is now or do I need to actively stabilize the pH so it can't go higher? What if I prune back the macro?

Tanks stats:
- somewhere around 8-9wpg...tough to tell because the light isn't close to the water for heat reasons
- using R/O for topoff and new saltwater
- 1.025sg
- ammonia/nitrite 0
- nitrate 0 or so close to it that it doesn't give me a reading (was around 5 before the macro went nuts)
- kH was around 12 last time I checked but I will check again tonight
don't have other stats on hand atm

 

[Matthew5664]

Dose this help?

 

[Donya]

That makes sense; I am used to pH fluctuations that remain within the normal range...but it doesn't really explain a case of the pH going up at a steady rate without any help from extra buffers. That page shows how to get the pH up, but I'm not adding anything like it describes

 

[SkiFletch]

Yes, the macro is the cause. Reason: it is growing so fast that it is consuming all the CO2 in your water faster than it can be replaced by diffusion. CO2 lowers the pH so removing it raises the pH You'll probably get to a de-saturation point eventually where there is truly no CO2 left in the water and it will stabilize at that pH.

 

[Donya]

I hope it stops somewhere around 8.4 then it's still going up. I don't really want to mess with the pH since I don't want to cause unnecessary swings.

 

[Donya]

8.55+ and going up at a steady rate still and my tank is turning into an aqua-jungle...