CO2 measurement in wet/dry vs cansiter filtered aquariums.......at night

I left my CO2 meter on the tanks to see what rate of degassing occurs in my tanks with wet/drys vs canisters.

I have a 60p ADA tank that's non CO2 that has a canisiter filter as a reference.
It reads 2-3ppm

My 180 read 78-80ppm at the end of the light cycle and then never got much below 15ppm and that took most of the night, even with 3000gph+ 400gph+ 1000gph on water movement and rippling.
My 60 cube with wet/dry, dropped to 3-4ppm inside of 1 hour from 45ppm.
My other canister 60 Cube dropped to 10ppm this morning from about 50ppm.
My 120 ran about 56ppm at the end of the lighting cycle and dropped to 3-4ppm inside 1 hour as well.

This was just the factory calibration for the CO2, but seems somewhat reasonable over all.
I had several tanks to compare to and they where consistent.

I need to do 2 things still:
1. Calibrate using a referenced DI/RO + sodium carbonate solution and pH meter, then compare that known CO2 to the CO2 meter readings. Bubble N2 gas into a smaple to remove all the CO2 and O2, measure that. And finally remove the water from the reference pH tank and add some tank water to note any in tank differences in readings.

2. Measure O2 as well. Why? Well for the fish for one. Second, the gas exchange is much slower in the canister tanks, so if this is true for CO2, it should apply to O2 as well.


I think surface films might hold the CO2 in the canister filtered tanks longer.
Same should apply for O2 from plant growth, but this should decline due to use by fish and bacteria.
I know it's not likely due to the filter's themselves.

Why? Well, the non CO2 canister reads a steady 2-3ppm all the time.
So 2ppm or so added due to canister is reasonable, but not much more.
Sediments also play no role, I have paired types is each filter type(plain sands vs ADA AS)

The flow in the canister tanks is really high, much higher than the Wet/dry tanks.
I would expect some difference, just not this much and the rate of degassing I would expect to occur much faster. I'm concerned more due to the fish and their exposure to chronic CO2 at night. Most focus on CO2 during the day only.

These tanks also are more sensitive to gassing fish than the wet/dry tanks.
I need to do more here and shall.

I think so far, I'm thinking of going all surface skimming sealed wet/drys.

The cards and most of the plecos do well even at the higher CO2 levels, but.......they could do even better and have less stress at night nonetheless.

Regards,
Tom Barr

 

Well, I also have a Neptune aqua controller pro 3, so full pH control is rather simple also.
I'm referencing the pH with a reference KH method for the DI/RO make up. Then running the actually tank water vs the reference water with the same rate of flow.

For the client's tanks, he uses RO/DI reference water already now. But there's a lot of wood and other things that can alter the KH/pH over time.
The goal is to see what difference that is and if so, how to adjust for it.

By using both methods, one as a reference, and another as a non pH/KH method, we should be able to note any differences.
Also, comparing CO2 ppm's changes over time and with different types of filtration and O2 levels, should give us a good indication what is optimal for fish.

The CO2 meter also detects differences within the aquarium, something the pH seems poorly suited for, so in one location, it might be 80ppm, but 100cm away, it might be 40ppm, in the plant beds where the water is still, maybe 15ppm.
So WHERE is important as well. I just chose a specific spot that was similar in every tank out front where the current was good.

I add the probe to this same spot for a reference point.
So it's just a slice of that tank, not representative on the entire system.
For that, you need to do more work and more data points in each region, cocurrent current readings would be nice, but not practical for me just yet.

Regards,
Tom Barr

 

Thanks, good to know.
Seems like the probe is calibrated, but I'll verify this wekend perhaps.

Regards,
Tom Barr

 

Naw, about the same, I get really weedy growth in my 120 Gal, I have been reducing the light and messing with that for some time now.
I get strong growth in the 120, they have similar bioloading and flow etc, light is a bit different, the 180 still has the 96W PC lights, they do not make a decent t5 72" long Tek hood and I do not wnat 2x 36" hoods hanging over it, but might end up havign to at some point.

I just do not think canisters are all that good for the fish health/stess.
So I'll likely be upgrading my tanks to all wet/drys............now I already have the chambers and filters...........it is not like I was not already long thinking this years ago
I just want to look at it a lot more and then make a more informed conclusion.

It is also FAR more easy to clean a wet/dry system vs a cansiter. I also need less flow/current, so there's less demand for that relative to the fish and less likely to gas the fish with lower O2.



Regards,
Tom Barr

 

His(Amano's) tank at home does not have one
It's a sump and a large surface skimmer.

That should tell you something.

George Booth long argued in favor of wet/drys, as did I some 15 years ago.


Regards,
Tom Barr

 

So, guessy what happened during a water change?

CO2 was still decent, 10-15ppm range from the tap water(hence the advice with algae often times).
I did 90% to remove any residual CO2 left in the 180 Gal, which is all cansister.
I'm doing the same to the 120 Gal which is wet/dry.

The 180 started out with about 25ppm and went down to 15ppm(no added CO2, done 1st thing in the morning)
Same for the 120 Gal, but the starting CO2 is 3ppm in this tank and the CO2 jumps to 15ppm after the water change.

The non CO2, I tried a few different methods recently.
I had been doing water changes with tap, but this time (well, the last 4-5 weeks), I used pre dechlorinate water in buckets that had been sitting for 1-2 days prior, so the CO2 is low.
This seemed to have a much more positive effect on fish and anti algae in the non CO2 tank. The tap is rich in CO2.........the sitting water is not and more similar in CO2 like the aquarium.

This goes back to my old theory about why we should not do water changes in the non CO2 planted tank, or.........how we can and not get algae blooms.
It's tied to the CO2 status of the plants and algae's detection, not nutrients or light(which is the same in most all cases or independent of water changes).

Nutrients we can test for, but.......we a good meter, so can we do the same over time for CO2...........and what do you know?
There's strong correlation with the CO2 ppm and algae issues with non CO2.......

By allowing the tap to degas and having good CONTINUOUS measurement of CO2 as the process unfolds............. you can see if the hypothesis is validated a bit more as you try and falsify it.
This is how you go about things, you try and disprove what you think is true(or tentatively verify it till you can figure out some other way to test the validity or someone else does etc).

Regards,
Tom Barr

 

My conclusion is based on fish stress/health, optimalization, not plant growth.

The ratios of CO2:O2 are lower with the wet/dry over all.
This means/implies easier breathing.

For plant growth, it likely is better to use a canister.

Trade off?
Fish or plants?
Well, you can still have nice results and effective growth without a canister, and have optimal fish gas levels, while the CO2 does get a little high during the day, this is off set by higher O2.
At night, the loss of CO2 and smaller loss of O2 and eventually increase of O2 later in the night.........out weighs the canister.

I'll post some O2 data from the same tanks and you can make the ratios.

Regards,
Tom Barr