Nano culture PH

[scooter413]

I have been losing cultures left and right and I have all about quit trying to culture these, but a part of me keeps going and going. The question I have goes along with a zooplankton question so I will ask it here as well. In trying to find a cause of cultures crashing 8 days in, I started checking the PH of the culture and found it to be very high right before it crashes. For example my nano culture at 7 days has a PH of 9.7-10.2. This was check by a calibrated ph meter. The nano culture next to it that had already crashed was a 6.2. Could there be something that makes it spike that high and kill the culture or is it ok to have them that high. The second part of the question is that I was feeding a copepod tank with the cultured nano(before it crashed) and it is in the process of crashing as we speak and the ph of that tank is about 4.5 ph. The only thing that is in the tank is filter pads and a slow feeding air line creating slow bubbles. Would the the dying phytoplankton cause the ph to drop therefore killing the copepods.

[Luis A M]

Yes,thriving phyto cultures reach very high pH values when in peak condition.This is produced because algae consume all the CO2 of the water.No cause of concern.
The opposite is true when WQ deteriorates and CO2 rises;pH drops.Though the value you found is extremely low You sure the meter was well calibrated?.Try to bubble strongly the medium for some time and check again...