DIY co2, pH, and guppies

[pud2224]

Amm 0
nitrite 0
nitrate 20
temp 79f
planted tank (14 different plants)

1M, 2f guppies
1m black molly
5 cherry barbs
2 adf's

20g running since Xmas.

pH before diy co2 was 7. I setup up (2) 2L co2 generators (sugar&yeast) and bubble counter diffused into hob intake on Thursday. Friday I checked the pH again and it was down from 7 to between 6 and 6.2 hard to tell. So I took off a 2L bottle and had 1 run from last night. I just checked and pH is 6.6

Reason I'm looking for help is 1 of my guppies aborted (not sure when she is/was due) and I'm chalking it up to the pH swing. Would you agree?

Also, is there anyway to control pH without a drop checker which I don't have or a controller? Should I disconnect the co2 setup at night and let it bleed off into the atmosphere? then hook 1 bottle up for daytime?

And will the pH rise back to normal without doing wc's?

If anymore info is needed please ask.

 

[bgmann12]

I run a powerade bottle for mine with an airline valve on it to regulate the flow somewhat.

 

[Fresh2o]

If you are concerned about excessive (and unused) CO2 at night, you could run an air pump (or additional filter) connected to a timer that comes on after the lights go out. This should gass out any existing CO2.