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drop checker


10 Feb 2009
hiya set my tank up 3 days ago added a few plants.Today i started with the co2 (been wating for bottle from ebay) unfortunatley im unable to use bubble counter on regulator just yet needs a rubber seal it leaks co2 so i bi passed this i wonder if anyone can help. i set drop checker up for first time got a few probs i put 3 drops of the solution in drop checker and used de-ionized water to top it up till ball just over half full it turned yellow put it in tank and its stayed yellow indicating too much co2 which cant be right as ive only just started using its only on low as i cant check it no bubble counter.many thanks


New Member
14 Feb 2009
Hi Tyke,

My guess would be that because you have used de-ionised water in the drop checker (which has zero/v.little?? KH) that the colouration will be inaccurate. I haven't done the maths to say for sure that a small amount of CO2 would cause a DI drop checker to turn yellow, but it certainly won't be correct.

Someone else will be along to give further advice, but my recommendation is to get some 4dkH solution (aquaessentials sell it) for your drop checker and possible another bubble counter to further control your Co2 injection. The '4 degree KH' solution will mean that a standard KH is used so that the KH/pH/CO2 relationship is most accurate. With this in the drop checker (DC), when it turns lime green (which I believe is a pH of about 6.6) you will know that you have 30ppm CO2 at the surface of the DC.

Maybe someone will be able to post the link to the KH/pH/Co2 table for further clarification.

Hope this helps,


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