Drop checker accuracy

**bennyc** · 16th Jan 2013, 09:54

I read that the CO2 test solution is more accurate if it is mix with 4dKH. Do not really understand the term accuracy here, If i am going to use water from the tank. Is there going to be a vast difference from the "real" value? Is the difference something you can live with?

How long will the solution last before i need to change? 14days?

Your guidance is valued.

**li_gangyi** · 16th Jan 2013, 12:11

To get any kind of real accuracy, I'd get a solution that comes premixed with 4dkh to not have to mess with this stuff, you really need 4dkh to have an idea how much CO2 is in the tank, if you use the water in your tank, you won't know the concentration of CO2 that's in the tank. I.E say the water u put in has a pH of 7.2 and it's KH10, 30ppm of CO2 will only cause the pH in the drop checker to drop to 7, not enough to turn the solution green.

Some people recommend changing the solution every water change which I find extreme, personally I wait till it's faded (where I can no longer read it's color properly), then I change it, have no idea if the accuracy drops off though.

**bennyc** · 16th Jan 2013, 12:31

Thanks, very "deep" but i now understand the logic. Haha. By the way is drop checker useful? It is a impulse buy for me.

**li_gangyi** · 16th Jan 2013, 12:54

It's a relatively accurate and cheap way to tell how much CO2 you're injecting into the tank. So yeah it's useful, especially during the initial setup to avoid gassing your fishes to death. It doesn't respond immediately though, it takes like 1-2 hrs for the indicator to change. With some twitchy needle valves, you'd preferably want a bubble counter as well just to get it into the ballpark, then depend on the drop checker for that final fine tune.

Your plants (and algae) however are the long term indication you have enough CO2 in the tank.

**milk_vanilla** · 16th Jan 2013, 21:51

Very useful, and indeed accurate.

**bennyc** · 17th Jan 2013, 11:21

Thanks everyone for sharing. A drop checker adds beauty to the tank too.

**li_gangyi** · 17th Jan 2013, 12:07

Not so sure about adding beauty to the tank myself. There are versions out there that hang by the outside of the tank, but require you to maintain the water level pretty high for them to work properly. To me those look better especially if you have a small tank, alot less obtrusive.