bpimm

From the looks of the design it could just float in the tank also, only problem I see is you would have to hunt for it to check it.

I run my CO2 24/7 and the indicator solution stays the same color night and day. Maybe the plant uptake is a minor part of the total CO2 injected into the tank so the CO2 content of the tank water stays the same whether the plants are using it or not.

swifty1

Nah, i didn't really see any real difference in response times between the 2 styles. They both changed to green within 2-3 hrs, although you can see a colour change within about 30 mins.

I run my Co2 24/7 so don't notice any subtle colour change overnight.

When i first installed them the teardrop shaped one was almost yellow so I tuned down the Co2 a bit.

I've just bought a solenoid valve so may add this to the bigger tank overnight, pureley to save on Co2. If I notice any colour change overnight when I fit it I'll let you know.

redstrat

Thanks Swifty, I was just wondering if there is any efficiency difference between the two designs. It looks to me that one of them has more air space inside. It seems to me that a larger internal air space would slow down the color change time, but I'm sure surface area is a bigger factor. Surface area of the tank water interacting with the air in the drop checker and surface area of the indicator solution. I'm glad to hear that my suspicions are either false or this just is too small of a scale for it to really have an effect.

hoppycalif

Logically I would expect the fastest reaction from one with a large area of contact between the tank water and the air gap, and, because the amount of water in the bulb is so small, the area of contact between the bulb water and the air gap would be a secondary factor. I'm not sure, but I doubt that the length of the air gap would enter into it. But, a large air volume would seem to slow it down. I don't know anything about the equations that would govern the rate at which equilibrium is reached between a pocket of air in contact with water, so intuition is all I have to go on.

dawntwister

I see a lot of simple designs for the drop checkers but I don't see any mention of where to buy the fluid to put in the drop checker. Where do you buy the fluid to put in the drop checker?

fredyk

I was wondering if I could heat a test tube thing on the gas cooking range, fill it with sand or salt, and bend; or would the heat distribution be inadequate?
Mark

swifty1

I received my two types of drop checker from HK recently and have to say that I'm extermely pleased with both of them.

It was fiddly trying to get 4 dKh in distilled water, especially as i was running out of KH reagent but finally did it.

the drop checkers seem decent quality and both look good. My comments on them are that there are no instructions with them and the reagent is from a CO2 tester and doesn't mention using distilled water of known KH or anything - just 5 drops of the reagent into 'some' tank water. Oh. and why oh why do thye come with black suckers rather than clear ones? These are minor points and would not stop me buying any more.

Thank god for this post which inspired me to buy them in the first place. I give them a glance every morning and has taken all the guesswork out about Co2 levels - it's already saved a lot of tests and calcs - thanks Hoppy!

redstrat

Swifty do you notice any difference in the two styles as far as response time for a color change. Does one seem to lag behind the other?

turbowagon

My drop checker (kH approx 5) still reads green the next day before the CO2 comes on again, which I guess is a good thing, but it surprised me. I confirmed that when I remove the drop checker from the tank, after a few hours the color is a deep blue (approx 7.5-7.6 pH).

I expected that much of the CO2 would outgass overnight, but I guess I was wrong. I run my spraybar horizontally at one end of the tank, angled slightly downward, which produces a slight surface ripple.

hoppycalif

My drop checker fluid goes to blue green overnight, then back to green in a couple of hours with the CO2 on. I was a little surprised at how little of the CO2 is lost overnight too.

fredyk: I don't think a gas range will be enough heat, concentrated enough to allow you to bend a glass test tube. If you try it, don't put anything in the tube, like sand, or it will make it much harder to heat up the area hot enough, and it will tend to imbed into the glass. The way real glass blowers do it is to slowly push the ends of the tube to shorten the test tube, thickening the glass where it is to be bent, then very gently blow into the tube as you bend it. That is a lot easier with a longer tube, of course. If you try this, be very careful!!