Guppy Deaths It Has Happened B 4

Hi,
I do and i don't and then i do and then don't use my pressurized CO2 and have been using my Probe and it always says 7 or 6.8 Ph........ but here is my little sad story ... if anyone cares :icon_roll

I usually always run a powerful air stone in my 90 gal.
it has two XP3's stocked with bio balls , UV 18w, and dormant CO2 right now.

Each time i try to ditch the air bubbler , i wake up to 3 or 4 of my Guppys dead :<(

I have been trying to get a drop checker at the LFS, but they are out and reordering.
Not really certain my Probe is calibrated and reading true ? Thought a drop checker would help.

I used a solution to dip the probe and it comes out at 7.

Not certain my calibration is accurate.

I probably sound like an idiot, i apologize.

Probably not giving a clear picture here, but i will throw this to the forum sharks.... be kind :>) i am sensitive lately. :help: :help: :help:

Glad to fill in any info anyone needs to sort out this Rambling Diatribe.