Why go to all the fuss of a drop checker when one can use a CO2 test kit? I have a LaMotte CO2 kit and am happy with it. Are you saying that drop checkers are more accurate?

I do not use neither, but I would guess that drop checker has the following major advantages:

1. it is always ON, you can check CO2 level as you pass by the tank;
2. it is cheaper.

Regards.

Vladimir.

The drop checker is also accurate, even if your tank water is high in tannins and phosphates. That isn't the case with any of the test kits that use KH and pH to determine CO2 ppm.

Yes i agree Even LaMotte admit this. I live in Australia. Where can i purchase a drop checker from? What does ADA stand for?

Does anyone have any experience with Dupla Permanent CO2 test kit?
LAKA

You can DIY, check Vaughn's many incarnations.

You can buy from many of the Hong Kong ebay places.
About 15-20$ US.

You'll need the KH ref solution and bromo blue pH indicator. Add 3 drops to 6mls of KH solution inside the drop checker, replace about 2-3 week intervals etc.

Getting the KH ref solution will be the tough part unless you or others "Down Yonder" there make it.

Regards,
Tom Barr

ADA stands for Aquatic Design Amano. That group sells a very nice looking glass one, but Amano doesn't use it. You are closer to Hong Kong than we are so the ebay one is your best bet: eBay Store - T 1Brian-Aquarium Plants Supplies: CO2 Diffuser, Water Conditioner, Fertilizer

LAKA, i have bought 2 of the drop checkers from ebay (broke the first), so yes you can get them in Australia (cost about $36.00 delivered). I also have 5lt of Tom's original 40°KH solution (4.99gr bicarb soda to 5lt of distilled water). Let me know if you want some of this. I can even dilute this down to 1lt of 4°KH solution if you can't do this yourself.

P.S. I have been using the drop checker method for about 6 weeks and its a very big improvement over any of the other methods to determine CO2.

Thanks for all the advice.
PaulB i will order a drop checker from ebay tonight. I should be OK with making the KH ref. sln-will follow VaughnH's recipe. If i run into any probs. i'll let you know.
LAKA