Confusing readings

[DARKPHREAK]

I am using 2 Nutrafin systems on my 75g and I just tested to see what the CO2 levels are from the table on Chuck Gadd's site. My pH is 6.4 and the KH is 4 dKH which is 71.6 ppm and I'm getting a reading of 47.773 ppm of CO2. I understand that this level is VERY high but I don't get how it could be this high with just these small kits and DIY mixtures. Nitrate is about 5ppm and everything else is nil. Because this is a newly planted tank, running about 2 months now, I havent added ferts due to the fact that I dont know what to add. I wanted the plants to settle in before tackling the fert aspect, but now that hair algae is starting to show itself I may have to add something soon.

If any of you planted tankers have any ideas what I can do about the high CO2 levels and what ferts I should be adding, suggest away.

[artw]

I have 2 yeast bottles on my 33 and my CO2 levels are routinely way off the charts (ph 6 KH around 4).

I am quite suprised to hear that these little Nutrafin things are enough to run a 75. (obviously from your tests you prove it is able to.).  I would think that using DIY Yeast co2 however is cheaper in the long run

[guest123]

I was also wondering the same thing.  I have a 77 gallon and 1 Nutrafin system.  I have my kH at 4 dkH and my pH at approx. 7.  I use both Seachem Acid buffer and Alkaline buffer.  In the correct proportion they bring down the pH from my tap water from off the charts to 7 and my kH from 2 or 3 to 4 or 5 if I recall correctly.  Does anyone know what their kH is from the tap water?

I was thinking of getting a pressurized CO2 system but as DarkPhreak mentioned, from the readings of CO2 already seems off the chart.

Can anyone comment on a pressurized CO2 system?  I am no longer sure if I need one considering the reading mentioned above.

[DARKPHREAK]

From everything I've read, buffers can and will give bad results but dont quote me on that. I have a .8 drop in my pH from the tap to the tank which is about right for the addition of CO2. If you have 4 dKH and a pH of 7 it means that you have 12 ppm CO2 which from this site http://www.csd.net/~cgadd/aqua/art_plant_co2chart.htm
is good. The advantage to pressurized with a ph controler is that you are able to keep the ph at a proper level and avoid the pH swings. The cost for this system is abit more then I am willing to spend right now, I lucked out on that bag of CO2 stuff at the auction. Although my pH has been steady for the past 5 days I know that as the yeast burns out that it will increase the pH. Im just curious what the other plant growers do to achieve proper levels in their systems.

[dpatte]

to keep my co2 steady i use 2 co2 generators and change one each 6 weeks

[Ron]

Hi Darkphreak,

I've never used the Nutrafin CO2 system you're using, but I agree that your readings seem high for a 75 gallon. From your second post it appears that you are well aware that adding any buffers or pH modifying chemicals will invalidate the chart readings, so I'm assuming you aren't doing that. Some municipal water supplies add buffers to tap water that could be playing havoc with your results - just a stab in the dark here; I don't know what Ottawa does.

The first other thing that comes obviously to mind is that you have some source of humic acid in your tank that is skewing your test results. Did you use any peat in your substrate, or do you have any driftwood in your tank? Decaying plant matter?

Another possibility might be the accuracy of your test kits. If you can, I'd cross reference them against some other kits to see if the problem lies there. (if I can make it to the next meeting, I'd be happy to help you with that - let me know)

Finally, does the appearance of the tank bear out your suspicion that the CO2 is high? At that level, the plants should be pearling like crazy, given that they have enough light and other nutrients.

Best,  Ron

[guest123]

I do use Buffers in my tank.   From what I understand this invalidates the chart for determining the CO2 level from the KH and PH.  Is that right?  Is there any other test I can use to get the proper CO2 readings?

Does anyone recommend a good water chemistry book that talks about all this?

[DARKPHREAK]

Ron,

To be honest the plants arent doing very well at all, I've had an ongoing problem with BGA so most of my stem plants look horrible.  Im using Florite and sand as a sub, with a few jobe sticks placed near the stem plants. The plants are not pearling but are streaming, least some of them are. I suspect that my reading are false and I will get another kH test kit soon just to make sure. Looking through the bottom of the tank I can see that the root system is doing VERY well. I had been running carbon in my filter and realized the it was taking things out of the water that the plants need. I will leave everything alone for a few more weeks to see what happens. Would like to make it to the next meeting but I work shifts and on that Monday I will be working 8pm to 8am so I'll try to make it to the next one, thanks for the offer for testing. Guess its just a wait and see at this point.

James

[Anubias]

Hi,

It is very difficult to measure CO2, and I've never considered the pH controller much of an option. There are too many wild factors,  which has been mentioned in previous answers given. One can do a lab test on a fresh sample where the buffers etc. will not factor in. Unfortunately, one requires lab equipment.

If with adequate K, Mg, etc. and light the plants are not growing, then you are low on CO2. The key is the cyanobacteria in your tank. It indicates a low level of oxygen in the tank, or a high level of of DOC, or both.

Regards,

[luvfishies]

Have you tried www.plantgeek.net  ? Nice site with great mods and not condescending at all.