Co2 And Calculating It

[Evad]

I heard the following and would love to try this!

To test for CO2 - test your pH - you will need the "normal" range kit. Test your KH - some kits measure in ppm (mg/l) so you will need to convert into degrees hardness. Just divide ppm by 17.9 i.e. 60ppm = 60/17.9=3.4 degrees. Now cross-refer these two readings on a CO2 table - see the link in my sig. Example pH 6.6, KH 4 gives 30ppm CO2 - an ideal situation.

1) Anybody know where this table is? The link in the thread was dead - if anyone can refer me to a table that would be great!

2) If I am understanding this correctly, is it possible that my water parameters might be such that I will not need to supplement with CO2 to have a healthy planted tank? Or will there be more plants than the water has CO2 so you still need to supplement.

Thanks!

 

[Bignose]

Google is your friend: <a href="http/www.thekrib.com/Plants/CO2/kh-ph-co2-chart.html" target="_blank">http/www.thekrib.com/Plants/CO2/kh-ph-co2-chart.html</a> (this is the first hit I get when I search).

Most of the charts aren't super-accurate because they assume straight lines when the phenomena isn't linear. However, most are also close enough that the difference is well within the error of the tests available to the common fishkeeper.

Edited to add: This link http/fins.actwin.com/aquatic-plants/mont...7/msg00158.html has some very good information. This is probably the most complete one I've seen.

 

[Evad]

This helps a lot. Looks like my CO2 is 9 or 10 to start. I still am curious if your pH is 7.0 and your KH is 6 if you ever need CO2 supplementation. According to the chart it looks like your have enough CO2 already.

 

[Mikaila31]

I can't figure that cart out, but if you are using CO2 most people tend to shoot for 30ppm. This is higher than levels normally found in aquariums.

Edit this is the chart I've always used.

 

[Evad]

I can't figure that cart out, but if you are using CO2 most people tend to shoot for 30ppm. This is higher than levels normally found in aquariums.

Edit this is the chart I've always used.

Your chart is certainly easier to figure out - but after looking at it the data is identical. Thanks for the chart!

 

[xxBarneyxx]

The problem with these charts is that if you have anything in the tank buffering KH or PH then it throws them completely out. For example the substrate I use in my tank drops my PH by about 0.5 If I just went by what the charts say this could give me as much as 20ppm difference (this is all explained in Bignoses second link I htink but I'm at work so only got a chance to quickly look at it).

For example if I add PH down to a tank (God please noone ever use this horrible product) it will lower the PH and on the chart give me a different CO2 reading but in fact the CO2 levels will not have changed.

The best way (without spending a lot of money) to check your CO2 levels in the tank is with a drop checker.

Basically you need:
A drop checker - This is a small plastic or glass "bulb" that holds a small amount of liquid and when put into the water has an air barrier between the water in the tank and the liquid in the drop checker.
4dKH solution - this is one of the two liquids you put in the drop checker. This basically gives you a completely flat base line solution to work from so any changes to PH/KH in the solution are totally down to CO2 changes and nothing else (such as buffering agents in the water).
PH indicator - Just standard indicator used for checking your PH. If I remeber correctly it needs to be based on bromo blue (I think most PH kits are).

The kit below has the drop checker and PH solution:
http/www.aquaessentials.co.uk/index.php?...;products_id=77

Glass drop checkers can be picked up on ebay for a couple of pounds (and look exactly the same as the £50 ada ones).

The 4dKH solution can be made but you can also buy a bottle for £6 (which is a LOT easier and more accurate than screwing around trying to oven dry piles of baking soda).
http/www.aquaessentials.co.uk/index.php?...roducts_id=1447

All you do once you have these is add around 4mm of 4dkh solution to the drop checker, add a couple of drops of PH solution, put the drop checker back to gether and turn it upside down (so when it goes in the water it catches a pocket of air in it) and place it in the water.

The PH indicator will start off a dark blue and will move up to a green/light green/yellow. When it is a lighter green colour you are at around 30ppm. One important thing to note is that it can take a couple of hours for the colour to change so if you are adding CO2 to the tank do it a little bit at a time, give it a couple of hours to catch up and bring it up a little bit more.