How low to let pH go during cycle?

[shawn_in_va]

Ok...I've read lots of posts about pH dropping during the intial cycle of a tank. Basically, it seems the summary is to not worry about the pH value itself as long as alkalinity is ok. But I'm looking for some support...

I'm in the process of cycling a new tank (24gal nano). I added 30 lbs LR on Saturday. The pH has been slowly falling since then (it started at 8.2 before adding the rock, this morning it's reading 7.5). My alkalinity is 4.00 meq/L. I have been adding B-Ionic over the last couple of days. Ammonia is defintely rising, and nitrites started to show up yesterday.

My question is this: is it truly ok to just let the pH drift down? Or is there a pH value at which I should start to take some action? If so, what's the best action to take? I worry that anything I do would push the alkalinity up to a level that's not good.

Thanks in advance for any help or suggestions.

Shawn

 

[Randy Holmes-Farley]

I'd personally try to maintain the pH at at least 8.0 with limewater. At pH 7.5 it risks starting to dissolve the calcium carbonate shells and skeletons of different organisms.

 

[shawn_in_va]

Randy - Thanks for the quick reply. So I assume my best approach is to start to add the limewater, and hold off on the B-Ionic, so as not to drive my alkalinity too high?

 

[Randy Holmes-Farley]

Limewater has a bigger pH rise for the amount of alkalinty added, and it also adds a proportional amount of calcium, so that alkalinity does not rise relative to calcium (B-ionic has that latter part too).