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.

hoppycalif

Last week I took a trip to Tap Plastics, where I bought a 1" dia, 1/16" wall thickness acrylic tube, to go with my existing 5/8", 1/16" wall acrylic tube, and some acrylic disks - 1", 1/2", 5/8" diameter, plus a tube of medium viscosity acrylic cement. Then I spent a couple of hours yesterday and a couple of hours today, using only hand tools plus a cordless drill to make a couple of DIY drip checkers. The first one is probably the fastest reacting one:



The second one is probably the easiest to read the color on. I used white fingernail polish to paint the inside of the air gap tube which becomes the background for the fluid in the bulb.



Tomorrow I plan to load both with distilled 5 dKH water and reagent and place them in the tank at the same time, to see how they compare. I will post those results, too.

Edit: Today I loaded them and added them to the tank.


Edit: After two hours all three of the devices have the same color. The one with the white background was the slowest to get started with the color change, by a half hour or so, but once they were all changing color, both of the DIY ones ended up with the green color at about 2 hours. Now, I'm not sure what affects the response time of these, but I am sure that both of these DIY designs work well. (Both of these have been spoken for now. Maybe someone else would like to start making these and selling them here?)

redstrat

Hoppy just currious, whats the cost range for one of your DIY drop checkers???

hoppycalif

The cost of making one of these is hard to say. Tap Plastics, or at least my local store, won't sell small pieces of acrylic tube, so I bought 5 foot long pieces, which are about a dollar per foot. The little acrylic disks are about 50 cents each. And the cement is a few dollars for a tube big enough to make a hundred or more of these little things. The suction cups are "Lee's Heater Holders", two per package and a couple or so dollars for the package. I didn't have disks to fit inside the 1" dia tube, so I used a 1" hole saw to cut out pieces of 3/16" acrylic for those, since they needed a hole down the middle anyway. The cost of that is as near zero as you can get. I'm guessing my cost for each of these would be around $3. When I get thru with these, probably tomorrow, I will give them away for the $4.50 cost of priority mail plus PayPal fee plus $3 for the materials - $7.50, and one has already been spoken for. The Red Sea version on EBay just went for $14 including shipping, so this is still a bit cheaper, especially if you already have a pH test kit, and it's a lot cheaper if you make your own. (Providing you have a use for the left-over tubing and cement.)

fredyk

Hi Hoppy,
thanks for offer-taken you up on it. Tried to make one over the gas stove burner. beginners luck- it sort of worked, but the glass elbow broke. two more attempts did not succeed.
Mark

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turbowagon

I thought of a situation where these drop checkers could potentially indicate a higher concentration of CO2 than is in the tank, when using a CO2 mist application.

Suppose the mist bubbles accumulate a little pocket of CO2 in the air chamber of the drop checker. If these bubbles are accumulating faster than they can dissolve, there will be an artificially higher concentration of CO2 in that little air pocket than in the rest of the tank. Since the little chamber of water in the drop checker is very small, the CO2 levels will become in equilibrium with the air pocket a lot faster than with the tank.

A way to test this hypothesis would be to surround the drop checker with a shield that prevents the mist bubbles from entering the chamber and seeing if the indicated CO2 level changes.

Fome

Mine cost about $1 for the container.

Suction cup, cement, and ph indicator wasn't included in price, however because I had all those things on hand.

hoppycalif

That is a potential problem, but I don't see it as a serious one. These things reach equilibrium pretty slowly, over a couple of hours, or so. So, unless there is a steady stream of CO2 mist bubbles gathering under the "horn" of the device, then dumping their remaining CO2 into the air gap, all that should happen is that the indicator will "overshoot" the true CO2 value, but settle down to an accurate reading eventually. If the ppm of CO2 in the bulb of the device is above that in the water, the CO2 will migrate back to the tank water.

I think the problem can best be avoided by choosing a good location to mount the device - where there is good water circulation, and at the opposite end of the tank from any mist generation. Those CO2 micro bubbles can't exist for very long in the water, before the CO2 diffuses into the water, leaving a microbubble of other gases. So, I suspect that most of the bubbles are "inert" by the time they are swirling around the opposite end of the tank.

Minsc

For those of you who don't mind your D.I.Y. being a bit U.G.L.Y.,
I present: the rigid airline "M"


Cap one end of the airling with masking tape, fill it with salt to within a half inch of the top, cap the other end, put it in a vice, apply heat via hairdryer, bend.

It aint pretty, but it didn't cost me a thing, and I don't plan on keeping it in the tank for very long