Sorry I misposted my numbers, I actually had a PH of 6.4 and a KH of 6.5, not a ph of 6.6..my bad. I put in my drop checker the next day and after some adjustment and increasing the Co2 it was at 30 - 40 ppm and the plants began to pearl like crazy. It most definitely was NOT at 70ppm like the chart was telling me.
And since many rely solely on the chart as their metric for CO2, how might this over estimation, this belief that their test method tells them that there is much less CO2 in there than is really the case....might affect plant health, growth and algae?
The chart might work for some folks, not for others. This is a known fact and observation.
So there has to be another issue occurring besides those 2 parameters, pH/KH.
The drop checker gets around that, but............how accurate is the color changing in the DC? Can you tell between say 18ppm and 24ppm of CO2 with a DC? After adding CO2, how long does it take for the checker to change color?
How often should they(DC) be changed? What about placement of the DC?
It's a rough guide and slow to change device.
You give up one good trade off, and gain another, without really knowing if the CO2 is accurate or not.
Algae, plants, eyeballs , Riccia stones, fish, shrimp etc...........all these are perhaps better test kits for CO2. Or a mixture of all 3 methods, livestock/bioindicators, CO2 charts, and DC.
Do not rely too heavily on any one thing other than livestock.
"They" do not lie.
But folks need experience and to be careful, CO2 kills 99.99% of the fish with dosing errors, so it demands respect!