dupla co2 permanent test help

[bass29]

Hi All.

Does anybody use one of these?

I've decided to fire up a new plant tank after a few years break from the hobby but no longer have my tester instructions.

I have some fresh reagent. Am I supposed to fill the bell with tank water and then add a certain number of drops?

Thanks!

 

[plantbrain]

Try searching DIY drop checker for CO2.

You should pull up many, they(the above type) use a reference KH solution and bromoblue in a glass/plastic chamber.

They are slow to respond, so the levels are good if you account for them.

They need changed about every 2 weeks or so.

Regards,
Tom Barr

 

[bass29]

Thanks Tom. Found the info - 3 reagent drops to a chamber of tank water.

I miss my probe. Has anyone had experience with the aqua medic probes? They're almost half the price of the dupla ones here. Can't afford the dupla, but was told that the cheaper probes have variance as high as +/-0.5 whereas the dupla has +/-0.2

 

[plantbrain]

No, they are not that different.
Any standard probe connector ought to do fine.
Most any lab supply place also sells them and are much more accurate, I know of no pH probes that claim 0.5pH unit accuracy

That's fear mongering by Dupla marketing (or likely their distributors etc)perhaps....0.2pH units is pretty bad for that matter..........

Your calibration and movement/float will tell if they are decent and well cared for.

Also, pH alone does not tell if the CO2 is truly accurate, which is why things like peat, non bicarbonate alkalinity can skew things, as well as other weak acids than CO2(eg tannins).

Which is why the drop checker using a reference KH gets around that.
Problem is the trade off is that they slow(2 hour or so response time) and the color resolution is only maybe 0.2pH units at best.

There are other more $$ probes and adaptations you can do to convert a pH probe to a reference KH probe CO2 monitor....but it's sort of outside the hobby range.


Regards,
Tom Barr