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

[Tom Barr]

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

 

[dutchy]

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.

That's kind of high. I would be worried about fish health day AND night. With a pH controller calibrated against your CO2 meter you would never hit 80 ppm. It can work well, I guess my tank shows that. I know you don't really like them, but why is not totally clear to me. If you use a good way of calibration it can't be that much off.

regards,
dutchy

 

[darkoon]

i experienced the same issue with my eheim sealed wet/dry filter, had much lower CO2 ppm every morning, finally decide to switch over to a regular canister, co2 ppm is much more stable now. same issue with surface extractor. I normally use it for 5-10 minutes everyday to get rid of surface film, but if I forget to turn it off, i can see a significant color change in the co2 drop checker.

 

[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

 

[Oreo]

I'm glad you did this test Tom. I've noticed the same thing from my aquarium using a canister style filter. Granted, I'm only using a pH probe & careful observation of other signs but I've been quite certain that there was still a significant CO2 residual in the morning. Someone at one point was swearing up & down to me that this was impossible but I knew better from my own experience.

 

[shoggoth43]

Tom,

Just to clarify since I'm not sure what changes you may have made recently.

Cannster on the 180 and Wet/Dry on the 120?

Another thought, how are you dealing with overflow noise? Any major air injection or turbulence in the pipe ( gurgle buster or similar ) would probably increase the out gassing significantly. I'm not sure if just sealing the biotower is the most efficient approach or if dealing with the overflow first would be best. Most likely both would be the most efficient.

-
S

 

[yme]

well... these measurements correlate pretty well with mine.

with a canister filter only, you are not able to degass the tank O/N.

greets,

yme

 

[Tug]

I removed all of the biological filter media except for a few sponges just the other week. I was hoping it would help reduce the number of nitrifying bacteria and improve oxygen levels. But if I remember correctly Tom, you are already doing that.

 

[fjf888]

Is there any difference in terms of the amount and quality of growth of plants in the wet/dry vs. cannister only tanks? I assume this would be tough to measure objectively without having controls for other factors like livestock, substrate, etc.

 

[Tom Barr]

well... these measurements correlate pretty well with mine.

with a canister filter only, you are not able to degass the tank O/N.

greets,

yme

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

Regards,
Tom Barr

 

[Tom Barr]

Is there any difference in terms of the amount and quality of growth of plants in the wet/dry vs. cannister only tanks? I assume this would be tough to measure objectively without having controls for other factors like livestock, substrate, etc.

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

 

[fjf888]

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.

Heheh, we all know that from being on here, but there you go stirring up trouble again You start with adding KNO3, PO4, EI, HLD, and now you challenge yet another planted tank so called golden rule, the cannister filter. What's next

 

[nipat]

This makes me wonder which one plays the main role, between the sump and the surface skimmer.

>>> another planted tank so called golden rule, the cannister filter.

The general golden rule in planted tank folks, may be. But I read it in aquajournal.net.
that Amano himself is not sure if the canister type is ideal either (CO2 issue).
http://aquajournal.net/na/stories_behind/index.html

 

[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

 

[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

 

[dutchy]

Couldn't you have done this experiment 6 months ago, Tom? I could have bought wet/dry's.

I was also wondering why I still have some CO2 in the morning, with my inaccurate measurements 13 ppm. I have 2000 gph of flow and a good ripple. Now it's clear. But this also means a lot of CO2 degassing duriing the day. You have to take that into account when dimensioning the CO2 equipment I guess.

Well, good to know for next time, for now the two cannisters will have to do. :gw:

regards,
dutchy

 

[Whiskey]

I think I'm not understanding something here,..
If I read the first post correctly you found that using a canister filter lead to better CO2 retention during the dark hours where CO2 is off. Then you theorized that this probably indicated that the 02 which was created during the day was also better retained throughout the night when using a canister filter.

Then you concluded that you should go to all wet drys, and get rid of your canister filters.

I don't understand,.. why would better retention of CO2 and O2 be a negative thing? That means the environment is more stable, and it also means that the fish have more to breath better protecting them from high CO2 levels.

Please help me understand where your going with this
Whiskey

 

[pat w]

I was a little confused, too, until I reread for the sixth or seventh time. Let me see if I have it right? Someone PLEASE correct me if I'm wrong.

The basic idea is that, with a canister, there is insuficient transfer across the surface film to fully degas the CO2. Since at night plants convert over to O2 consumers and CO2 producers the net result is a CO2 level that stays relativly high and an ever reducing O2 level presenting a gassing hazard to the critters.

If that is the case, could you just put the canister on a surface skimmer? I guess a better way of posing the question is .. is it the wet/dry or the surface skimming that is the desirable component?

Pat

 

[shoggoth43]

There's a couple of possibilities here. The surface skimming will definitely play a large role since you will have a large surface area constantly being moved.

I'm more interested in what happens AFTER the surface is skimmed. Does the water drop down a significant amount before being routed to a hose? i.e. splashing. Does the water go through any sort of gurglebuster arrangement which would inject significant amounts of air and thus turbulence leading to outgassing? Is the biotower sealed in any way to prevent outgassing from the water trickling through the drip plate and biomedia? Will the sealing of this biotower matter at all if you are pouring large amounts of air down the hose since it would need to go somewhere which means bubbling out the bottom of the tower? Could you "recycle" this air with a hose leading back up to the surface skimmer and thereby maybe reduce outgassing by reinjecting the relatively CO2 rich air back down the hose?

I suspect the easiest method would be to reduce splashing and then reduce any air going down the hose to minimize turbulence. Once this is done, sealing the biotower would probably get you the high CO2 outgassing at the surface without any unnecessary additional outgassing in the wet/dry. It may just prove to be a waste of time to bother with all that other than the benefit of no gurgling or foaming in the sump.

-
S

 

[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