CO2 <-> Ph / Kh

[Arne]

I have been wondering about something for the past 2 weeks, and I'm hoping you can put me in the right direction

I've recently set up an ADA 60p with ADA Amazonia substrate. As recommended I did water changed every day the first week and every other day the second week. I've been measuring Kh and Ph daily and trying to get a handle on whats happening. I've read about the Ph drop charts due to added CO2 etc and I noticed something I wasn't expecting.

Every day the CO2 starts 2 hours before the lights come on, and shut off 2 hours before lights out. At night I'm measuring a Ph of 6.8. This is with a Milwaukee PH600, stuck to the side if the lighting with rubber bands, sensor in the water. I've noticed the number keeps jumping up and down randomly if I hold the meter in the aquarium itself. taking out a cup of water doesn't give me trouble, I suspect because I can lean the meter onto something. So I shake off the bubbles, turn the meter on and wait a few seconds till it's stable.
Right, back to those readings...
I was expecting a drop of about 1 Ph, since my Kh is about 2 to 3 (10ml test). Yet the Ph only drops to 6.6, fairly quick and really steady. I don't have a drop checker (yet, didn't want one at first, ordered one now) but all the plants are pearling away 15 minutes after light on. As there is still a lot of green algae from the start up it looks more spectacular than it is but still...

At the start I was just dosing regular ferts generously and now I've started IE dosing, macro and micro.
Water changes done with regular tap water, tds 160, and the tank is tds 220.

Is there something I'm missing here, or could we just say this is normal ?

I'm expecting someone to say "add more CO2". I did that and didn't notice any change. I'm now at 2 bps for a 60L tank.

 

[Martin in Holland]

I have the same "problem" with measuring my PH (also have a KH of 2-3). With the KH being lower than 4 it's almost impossible to get a accurate reading of your PH so I stopped measuring and just look at my plant (and algae). I had a massive breakout of brown algae and looked into my lighting, CO2 and waterflow this is helping and I can clearly see my tank turning from brown to green.... Pearling of plants mean nothing, so don't look at those signs and think it should be OK.

 

[nybraby]

How do you measure KH is there a test kit or something ?

 

[Arne]

yes, 10 ml drop test