DIY drop checker - how long to equilibrium?

[Carissa]

Here is my diy drop checker. I figured that since it contains quite a bit of air and solution, and the surface area of water to air isn't much, it will take a while to come to equilibrium with the water. How much of a delay do you think I can expect between changes in the water and changes in the drop checker? Also since it's closer to the surface, would it actually probably read low compared to if I had it half way to the bottom of the tank? The whole thing is about a cup. I considered trying to put something inside it to reduce the volume of air but couldn't really figure out what to put in.

 

[VaughnH]

My guess is that it will take about 3+ hours for that drop checker to read correctly. The size of the opening into the air chamber above the fluid is small and that will also increase the reaction time. The photo looks like it is out of the water - was that just to photograph it? It does have to be completely submersed in order to keep the solution and the drop checker at the same temperature as the tank water.

If you can find a funnel with a larger opening, or a smaller jar to use with the present one, that might help.

 

[Gerryd]

Hi Carissa,

As a comparison, my Boyu type 1 DC takes between 2-4 hours to equate in my 180.......

Not sure how the sizes of the air intakes compare...


Nice job on your DIY model!

BTW, I ordered mine from over the pond (AquaEssentials) and was 9 days between order date and delivery date............. I ordered two just in case

 

[Carissa]

Good point about the difference in temp, how much would that affect the reading? It was just easier not to sink it because I didn't have anything to keep it below the water surface and obviously I can't cut into it to attach a suction cup. I'll probably build a new one or order one. Any other good diy ideas out there?

 

[FacePlanted]

Just about the simplest drop checker DIY design I could think of is to plug one end of a piece of 1/2" tubing and fill it with the solution and dye. Then bend the tube into an upside down U shape and attach it to the inside wall of the tank. Or, if temp. didnt matter that much, you could have the plugged end w/ the solution hanging over the rim on the outside of the tank, and bend the open end over the rim of the tank and into the water.

Pretty simple, but not very asthetic and maybe not entirely efficent.

Or cut the tip off a plastic turkey baster and glue it into the end of a .5" tube. Then plug the top end of the tube and fill it with the solution. Kind of like what you used in the pic, but using a tube instead of a cup.

???Maybe?? I dunno. There's a million ways I could think to make a ghetto drop checker.

I sat and thought of a bunch of different ways one day, but the best looking one was the one I bought from AquaticMagic. I think their ADA knockoffs look better than ADA's actually do. Just a matter of taste.

I give mine about 2 hours reaction time.

-Mike B-

 

[Tom Barr]

I saw a light reaction method that takes 30 seconds and is accurate to 0.1ppm of CO2 over a wide range. Cost a lot though
But boy, it would solve many issues

I'm trying to see about getting one and a nice light DO probe model for the lab
Then I can borrow it for a few days myself

Drop checkers are not fast, just keep that in mind when using them, there is an assumption they are always correct, but the question is less that, but more when is it that they are measuring relative to the color?

The lag time is long.

Regards,
Tom Barr

 

[dealt]

Pardon my ignorance but I'm starting to be confused in using drop checkers. Some clarification:

- if it takes 2-3 hours to equilibrium, does it mean drop checkers doesn't really display 'real-time' c02 levels. say at a given time, the indicator displays green, then it is the c02 level 2 hours ago?

- how frequent should one change the the 4 dKH solution and reagent?

Thanks!

 

[mrkookm]

I don't DIY my DC or solution but I have my Co2 come on 3hrs before lights on after realizing it takes about 2½~3hrs for mine to become mint tea green in my 90gal, open overflow and open sump setup. After lights out mine goes back to blue in 4~5hrs.

Pardon my ignorance but I'm starting to be confused in using drop checkers. Some clarification:

- if it takes 2-3 hours to equilibrium, does it mean drop checkers doesn't really display 'real-time' c02 levels. say at a given time, the indicator displays green, then it is the c02 level 2 hours ago?

- how frequent should one change the the 4 dKH solution and reagent?

Thanks!

No the DC isn't realtime but proper co2 evels can be assumed correct if DC is green. Recently through much reading here I have come to realize there are other factors such as plant uptake, plant mass as well as flow that can affect reatime levels.

I usually change my solution every 2 weeks max 3.

 

[Crazy Loaches]

2-3 hours doesnt seem that bad to me at all. My DIY design seems to take far longer. I've never really figured out how long it takes but I assume double that time. Next time I take it out to put new fluid in (soon) then I'll try to do it earlier in the day so I can observe how long it takes. I just need new reference fluid... I made my own batch (pain in the butt) accurate to within 1/2 degree KH (I measured it with double the ml of water) but somehow its gone bad. Maybe there was reminants of something in the glass mason jar I kept it in. Now, it goes green instantly when I add the pH fluid, and I've double checked that it is still within .5 of 4*KH. I'm stumped.

I saw a light reaction method that takes 30 seconds and is accurate to 0.1ppm of CO2 over a wide range. Cost a lot though
But boy, it would solve many issues

How much $ we talking here... hundreds? our thousands? Just curious.

 

[Carissa]

Just an update on my drop checker.

It does start changing color within minutes, but it probably takes about 2 - 3 hours to actually finish changing color.