Re: [GSAS-Member] Who's using a drop checker in their planted tank?

[Matt Staroscik <matt@wrongcrowd.com>]

Following up to my own post here--

If my checker isn't working as expected, the fault lies either with the KH
standard I made or the indicator in my drop checker package.

I tried the pH indicator from a test kit, which *should* be the same
bromothymol blue that came with the drop checker... and got a blue solution
from the standard, as expected. Bubbling CO2 through it sent it through
green and yellow too though I don't know the PPMs involved.

Maybe the Red Sea kit came with bad chemicals.

<shrug>

I put the drop checker back in the tank with the new indicator solution and
it seems like it is lightening towards green a bit. I have also turned up
the CO2 rate by about 1 bps because regardless of what the always-green drop
checker showed, the plants weren't pearling yet. We'll see what tomorrow
brings.

MS


On Wed, Jan 13, 2010 at 1:33 PM, Matt Staroscik <matt@wrongcrowd.com> wrote:

> I just installed mine but I think it is not working properly and I wanted
> another opinion. Obviously they are very simple and there is not much to go
> wrong, but I think my 4 dKH standard solution is bad. I have the Red Sea
> model, by the way, which comes with indicator, but no standard solution.
> They tell you to use tank water, which I don't want to do as the tank is 6
> dKH and has an unknown amount of phosphates etc in it.
>
> I made the 4 dKH standard myself with baking soda, RO/DI water and a series
> of dilutions. A KH test kit verified that it is correct, but as I used
> kitchen glassware maybe there was enough residue from detergent to mess
> things up. My RO/DO filter shows 0-1 ppm TDS as it should, so it is still
> working well... but maybe not well enough for this.
>
> When I added the indicator to the solution, it immediately turned green,
> about the shade of green that you want to see when the CO2 in the aquariumis
> at the right level. For a sample of the reference that has not had CO2 added
> to it, the solution should be blue, right?
>
> In the tank, the solution in the drop checker stubbornly stays green, even
> after the overnight lights-out.
>
> I put a sample of the solution + indicator into a graduated cylinder to see
> if it was sensitive to pH changes at all. If I blow in to it with a straw,
> the CO2 in my breath turns in yellow, as expected. Shaking it to drive off
> CO2 got it down to blue. The strange thing is, it stayed blue overnight. If
> the solution was off I would have expected it to bounce back to green when
> left alone.
>
> Some forum posts have said that drop checkers may not work right until they
> have broken in for a week or so, but that just doesn't sound right to me.
>
> Does anyone have ideas, and/or a convenient source of good 4 dKH reference
> solution? It's easy to make, but maybe not easy enough to make one that's
> pure enough in a kitchen.
>
> Thanks,
> MS
>
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