Determining CO2 levels (PH/KH method vs specific kits?) - Aquarium Plants

Rob

Hi all, (first post

)

Recently been looking at methods by which people measure the CO2 levels in there tanks. I have seen alot of refference made to the PH/KH method and indeed the various graphs and calculators.

Question is tho, I have also seen so called CO2 test kits (I beleiev JBL offer a "perma test kit with there CO2 system)
just wondering if anyone has any expereince of these? are there good ones and bad ones? or are they all about as much use as a chocolate teapot?

Thanks in advance, and congrats to Tom and everyone else behind this place.. Great stuff and well worth the $12 bucks

Rob

ervis

Quote:

Originally Posted by Rob

Hi all, (first post

)

Question is tho, I have also seen so called CO2 test kits (I beleiev JBL offer a "perma test kit with there CO2 system)
just wondering if anyone has any expereince of these? are there good ones and bad ones? or are they all about as much use as a chocolate teapot?

Rob

When I first set up my CO2 tanks system, I thought it'd be prudent to buy a C02 meter, if for nothing more, a sanity check while I got started. I can't remember the brand name, but I can describe it. It's a small plastic chamber partially filled with water and solution. The bottom is open, like a diving bell, or a floor hole in a submarine. The solution changes color as it reacts (indirectly) with the tank water. Blue is not much C02, Green is some, yellow is too much. Kinda worthless in my opinion, I took it out of the tank after about a week. I use the chart.

steve

Rob

Thanks for your reply

Sounds like an interesting contraption...Hmmmmm

In my original post I was reffering to these (last two items at bottom of page), Reading you reply again, I think they work on the same principle as you described?

Anyways, Thanks and I'll notch one up for the PH/KH method

Paul

Just use a normal ph and KH test kit and use the chart on this here

Rob

Quote:

Originally Posted by Paul

Just use a normal ph and KH test kit and use the chart on this here

Thanks for the link mate.

Thats more than likely the way I will go, question was more out of interest than anything.

Tom Barr

Use the chart and then if things still don't look good with decent nutrient levels and light, then take a leap of faith. Add a small amount more CO2 and see if things improve. Then add a bit more and so on........till your fish act funny etc and then back off.

If you have BBA that's actively growing something is still wrong.
There are a few things that cause issues with the chart, KH test are not accurate to 1ppm etc, pH test kits are not accurate(0.2 pH+,-)
stray voltage from lights, pumps etc can cause false positives with pH meter readings and pH controllers as can tannins/acids.

All in all, CO2 is not that easy to measure.

Therefore a good eyeballing of the plants is the best method in the end as well as BBA appearances etc.

Regards,
Tom Barr

Cornhusker

tom, its a hard lesson to learn after spending way over a hundred $$ on lamotte kits. O-WELL!

regards,cornhusker

m lemay

Quote:

Originally Posted by Tom Barr

Use the chart and then if things still don't look good with decent nutrient levels and light, then take a leap of faith. Add a small amount more CO2 and see if things improve. Then add a bit more and so on........till your fish act funny etc and then back off.

If you have BBA that's actively growing something is still wrong.
There are a few things that cause issues with the chart, KH test are not accurate to 1ppm etc, pH test kits are not accurate(0.2 pH+,-)
stray voltage from lights, pumps etc can cause false positives with pH meter readings and pH controllers as can tannins/acids.

All in all, CO2 is not that easy to measure.

Therefore a good eyeballing of the plants is the best method in the end as well as BBA appearances etc.

Regards,
Tom Barr

I'm consistently measuring CO2 in the 45-55ppm range in my tank. Is something skewing the measurements????

Could phosphate screw up the ph measurement enough to throw the measurements off that much?

These measurements are consistent with a LaMotte CO2 test kit as well as AP ph/kh tests and the charts. At a measured 30ppm in my tank algae is prevalent and growth sucks. Like tom said, the plants are the best guide. I keep a small surface current going at the rear of the tank just to make sure that the fish get enough O2 at night.

Marcel

Rob

Thanks for the replies all

Looks like I'll be going with the KH/PH method then, but I've never been one for testing, so I'm liking your method Tom

plus in the long run it makes more sense, its about adapting everything to my tank and plants.

Right.. So I'll aim to get the CO2 reading around 30ppm and then fiddle as nessecery.

Thanks again