Drop Checker Goo?

I never experienced the goo you are talking about but that is a good question whether this membrane could possibly prevent accurate readings. I'm curious to know myself.

Mine always changes to blue at around 4~5am (8~9hrs from lights off) every morning like clock work so you should be experiencing similar changes.

 

I have the same problem. Its caused by proteins in the water, that builds up on water surfaces.

More circulation and maturing of the tank should help. It might take some time.

 

Now that I'm thinking about this I've seen this film on tanks surface with misting and do notice the bubbles will get trapped under this film and gradually buildup. Factoring the above observation I would think this will skew results since it will trap the Co2 in/out.

Like I said, mine always goes back to goes back to blue...always.

BTW I assume your are using a good KH standard, not a home brew or a mix with Bro blue and tank water....right?

 

I don't think the drop checker will work right if there is a film on the water surface that is trapped in the drop checker. It works because CO2 can easily go into and out of solution across a water-air surface, but the membrane could be a substance that doesn't pass CO2 through that easily. I agree that it is probably a protein film, but I don't know how to control that other than by removing the drop checker, cleaning it and reloading it about every week or two. I'm guessing that the film takes several days to build up.

 

I get the same thing and my drop checker stays falsely green when the protein layer is heavy duty. It seems that CO2 builds up between the membrane and the testing solution. As my tank has matured it happens less, but it still occurs.

I pull mine out and clean that stuff out every other day (daily when I first started) -- but I still only change the testing solution once per week.

 

This is the most annoying snot to deal with. Within a few days it seems to clog up my diffuser and I am forced to immediately clear to as it impairs the consistent flow of c02. I figured that a bubble counter would help trap most of this but to no avail and after reading the comments on this post I can see why it wouldn't if a chemical reaction between the aquarium water and DIY yeast c02 is causing the snot to materialize.

If anyone finds a permanent solution to this problem, aside from switching to pressurized c02, I would love to know. Thanks.