Pearling

[levahe]

KH 4
7.2  -> 6.5 pH
7.6  -> 37.9 ppm CO2
 
KH 10
7.2   -> 6.5 pH
18.9 -> 94.9 ppm CO2
 
I take that to mean it kind of matters - That's why IMO a drop checker should be 4dKH so that lime green means 30ppm and so that you take out one of the variables by keeping the KH constant.
( I think the inaccuracy for 2 variables is the root of the sum of the squares - so better to measure one thing instead of 2)
 
I could be wrong tho

It isn't that simple and it doesn't need to be complicated either, the 1ph drop I state is an approximate figure. Depending on the water chemistry it may need a pH drop of 1.4 or it might be 0.7 at the other end of the scale, the point being if you advise someone to aim for a pH drop of 1 they won't be a million miles away and will be very likely to have a successful co2 injected planted tank.

People tend to over complicate things, I have never even measured the kh value of my water.
A pH test has advantages over a drop cchecker such as you can measure the pH in real time (drop checkers can take several hours to react) and can you tell the difference between ph7 and ph7.4 with a drop checker?

Drop checkers have their place in co2 injected tanks (I use one) but the pH test method will help you succeed and fine tune your co2

 

[SO19Firearms]

if you advise someone to aim for a pH drop of 1 they won't be a million miles away

If they have 10dKH they will - they'll be at 90+ppm CO2 with the example given above. That's a bit too much IMO

 

[Fluval-1200]

 

Within 2 hours of lights on I have a lime green (bit towards green than yellow) drop checker, it does stay that colour all day.
 
My kh was 0degrees and gh was 5degrees a couple days ago, will re check these tomorrow.

The drop checker needs to be lime green when the lights turn on
 

Yeah, It should be like that once ive set my co2 to come on 2 hours before lights.

 

[levahe]

if you advise someone to aim for a pH drop of 1 they won't be a million miles away

if they have 10dKH they will - they'll be at 90+ppm CO2 with the example given above. That's a bit too much IMO

I do the pH testing independent of the kh value, I don't even remotely consider it. I didn't even mention kh in any of my posts and it has no relevence to what i am saying. I know of the chart you are referring to and have no intention of using it,
Here is a recent discussion on the subject on another forum
http/www.ukaps.org/forum/threads/co2-sensitivity-in-otos-and-shrimp.29474/#post-307994

 

[SO19Firearms]

Here is a recent discussion on the subject on another forum

Ahhhh, I understand what you think now!