Co2 Readings

[BiffMalawi]

I have two planted 75g tanks.

Tank 1
2 Red Sea DIY Co2 units.
Ph 7.6 Kh 30 mg/l or ppm Co2 1ppm

Tank 2

3 red Sea DIY Co2 units

Ph 7.4, Kh 40 mg/l or ppm, Co2 3ppm

Red Sea units diffuse with powerhead reactors not ladders bubble size very small. They are connected to light circuits so only add Co2 during the photoperiod
Surface agitation caused by HOB filters is not excessive.
My tests kits say that mg/l is the same as ppm.
I used "Chuck's Planted Aquarium calculator to find Co2 level.
I checked with 2 different test kits(same brand different batches)
I changed yeast mixtures 2 days ago and visually they seem to be working.
I tested 4 hours into the photoperiod.

Now I know that DIY is inconsistent in it's out put but I expected that there would be more impact than this. Do these numbers seem to make sense to anyone? The Co2 levels are lower than my non Co2 non planted tank.

Thanks for the input.

 

[Themuleous]

Unfortunelty the trouble here is that the yeast based kits only really work on smaller tanks. Now you have 3 running on one tank, but for a 75g you'd need 4 or 5 kits to give you enough co2. A pressured kit would be better.

What mix are you using in the co2 kits, that could also explain the very low readings. Check out the pinned thread on the nutrafin kit which works on the same principle.

Also remember that test kits are not very accurate, i.e. a reading of 7.6 could actually be closer to 7.4. Similarly a KH reading of 30 could actually be nearer 40. These inaccuracies will affect how much co2 you 'think' is in the tank.

Sam

 

[BiffMalawi]

I am using a recipe as in the pinned thread but only changing them monthly.

I agree that presurized would be the way to go but cost of the intial set up is prohibitive and I have always been a little leary of having a pressurized tank in my home.LOL Of couse propane for the BBQ is an entirely different story.

The Red Sea units are rated as good for up to 40g. I know that this is probably ambitious but I would think that they would be sufficient for at least 20g each.

Does the level of Co2 take time to build up? Say I just added the DIY units yesterday, would my reading today be lower than on Tuesday? If I increased the amount of yeast and reduced the time between changes do you think that would help.

As the 2 75s are stacked have you seen any detailed info on setting up a shared pressurized system?

 

[sjdriscoll]

CO2 would take maybe a day to get to the magic 30ppm - BUT using DIY on tanks your size is very ambitious indeed!

I have 2 x 2l DIY in my 20gal tank - a 75 gallon would need 5 or 6 bottles all linked into one feed - and you would be changing almost a bottle a day to keep it all stable. You would pay for the pressurised unit in sugar costs very quickly!

If you do manage it, it would be very labour intensive, especially with 2 tanks going!

Good luck with what ever you do though.