My New Pet Hate!

[three-fingers]

i am not too sure about ponds, and whether there is a big difference to aquariums, there may well be higher CO2 levels than air, but once the plants start photosynthesisng this is quickly used and then the levels are lower than air.

Basically, it seems to vary hugely from pond to pond and tank to tank. In most cases (for both aquariums and ponds) there's always a higher CO2 level than allowed by the air-water equilibrium in the morning, whether or not it drops to or below the air-water equilibrium levels during the day is what will vary hugely.

It is all to do with Equilibrium:

If you are adding CO2 artificially, you are raising the levels high above the natural equilibrium with the air. In this case, the more aeration you have, the more CO2 you lose from the water. So an airstone can be a problem if you are artificially adding CO2.

If you are not artificially adding CO2, then the levels are never going to be measurably above the equilibrium point with the air.

That's not the case though. That would only be the case in tanks that get loads of water changes and/or gravel vacs and that have a lot of plant growth, like a high-tech planted tank without the CO2 injected.
In the average aquarium (which I'm taking as having normal ~20% weekly water changes, low-medium number of plants, medium-high number of fish and low-medium lighting), the CO2 level will be higher than the air-water equilibrium level due to all respiring organisms such as fish and bacteria breaking down waste.
Walstad tanks are the extreme version, where CO2 levels can be very high, due to the decomposing soil substrate and extremely low frequency of water changes.

But they can get below it, because the plants are using the CO2. So if you use an airstone in this situation, it will help the tank to stay in equilibrium with the air, and this will actually add CO2 to the water in this situation (although it will still be around the average of 8ppm - basically it keeps the levels steady)

In a relatively squeaky-clean tank tank with high light and nothing else limiting the plants, this could be a great idea (if you didn't want the fast growth from CO2). But in a small man-made pond (of which most are basically like large Walstad tanks), it would lower the CO2 level towards the air-water equilibrium.
I don't know where the "8ppm" level came from (an article or post somewhere?), but I'd be interested to find out. This level being mentioned supports what I'm saying - since water at equilibrium with air has 0.5ppm of CO2, much lower than 8ppm. The other 7.5ppm would be from respiring organisms.
But if this figure was from an experiment somebody on a forum had done using sterilised water and an airpump, I'd put it down to unreliable test kits.

 

[jourdy288]

It took a lot of effort on my part to move my fish from one pond to another..... all 5 (ponds) of them!..... not 3 weeks later, and with basic caution..... my hairy algea is back!!!..... How do I get rid of it forever, forever...FOREVER!!!!!..... I'll put pool acid in if I have to!... I hate the stuff! (fish gets tangled & die)

Whoa! I have decorated with the stuff and the tank looks attractive, but tangling and killing your fish

 

[aaronnorth]

It is all to do with Equilibrium:

If you are adding CO2 artificially, you are raising the levels high above the natural equilibrium with the air. In this case, the more aeration you have, the more CO2 you lose from the water. So an airstone can be a problem if you are artificially adding CO2.

If you are not artificially adding CO2, then the levels are never going to be measurably above the equilibrium point with the air.

That's not the case though. That would only be the case in tanks that get loads of water changes and/or gravel vacs and that have a lot of plant growth, like a high-tech planted tank without the CO2 injected.
In the average aquarium (which I'm taking as having normal ~20% weekly water changes, low-medium number of plants, medium-high number of fish and low-medium lighting), the CO2 level will be higher than the air-water equilibrium level due to all respiring organisms such as fish and bacteria breaking down waste.
Walstad tanks are the extreme version, where CO2 levels can be very high, due to the decomposing soil substrate and extremely low frequency of water changes.

The reason Walsatd style tanks have a low number of water changes is to stop the CO2 fluctuating (ie. raising the levels) which would cause algae, and to allow the build up of DOC. Note on Pg94 it says " CO2 may be depleted in the afternoon by heavy photosynthesis and then slowly return to normal levels at night" So how do we keep the levels raised constantly throughout thw day? Simple answer is surface agitation. Raising from 0ppm (as an example) to about 6-8ppm can be done through surface agitation, and it also means that the levels will not get higher than this (in the morning) because the excess will be gassed off.

I got the 6-8ppm from somewhere, although i cannot remember exactly - i will try and find it.

 

[Ludwig Venter]

It is all to do with Equilibrium:

Wow!!... Now you guys are starting to talk over the top of me...... In plain English,......Do I put a wead killer in there or,... do I have to live with the problem?

 

[three-fingers]

The reason Walsatd style tanks have a low number of water changes is to stop the CO2 fluctuating (ie. raising the levels) which would cause algae, and to allow the build up of DOC. Note on Pg94 it says " CO2 may be depleted in the afternoon by heavy photosynthesis and then slowly return to normal levels at night" So how do we keep the levels raised constantly throughout thw day? Simple answer is surface agitation.Raising from 0ppm (as an example) to about 6-8ppm can be done through surface agitation, and it also means that the levels will not get higher than this (in the morning) because the excess will be gassed off.

I got the 6-8ppm from somewhere, although i cannot remember exactly - i will try and find it.

Please do, I'd very much like to see it, because articles on the web and books (even non-aquarium books) list the water-air equilibrium CO2 concentration to be 0.5ppm.
Walstad herself states 0.5ppm it on page 100.

As such, what your saying doesn't make sense, and using an airpump will only serve to lower the CO2 until it reaches 0.5ppm. It would only raise it when CO2 is below 0.5ppm, which I find highly unlikely in most situations.

For instance, my 190l corner tank is heavily planted, heavily stocked and has medium lighting, and even with an airpump it's CO2 levels are around 15ppm in the evening before the lights go out, and they were even higher before I introduced the airpump (which I added because of the low surface area due to the shape of the tank).

I can see 8ppm being realistic for some tanks with airpumps, but the airpump is not beneficial at all, and without it the CO2 level would be higher, which would very much aid plants and could give them the edge over algae if light or nutrients other than CO2 aren't limiting.

Whether CO2 levels are depleted significantly during the day doesn't come into it unless they are depleted below 0.5ppm (which, as above, I find highly unlikely in most aquariums and ponds), where adding an airpump could be very slightly beneficial, but if your CO2 is at 0.5ppm I'd go ahead and guess that any thriving plants are making good use of alternative carbon sources instead (such as bicarbonates), or growing at an incredibly slow rate.

 

[three-fingers]

Wow!!... Now you guys are starting to talk over the top of me...... In plain English,......Do I put a wead killer in there or,... do I have to live with the problem?

Sorry lol Ludwig, we're basically having a small debate here, but i's relevant, I promise! It concerns the best way to get rid of your algae .

I'm mostly against algaecides, so I'd advise not to use any! It would only temporarily solve the problem, and could harm the fish over the long run. As you breed yours, I would say to avoid using any!

Using barley straw can work very well, but not always, and I don't like its use as you are basically letting more stuff rot in the pond. I would adise against it, and only use it as a last-resort measure. Personally, I'd rather just deal with the algae tbh .

As I mentioned before, what I would do is use water pumps to circulate the water instead of air pumps (which, as I'm trying to explain will just be making the problems worse). Once you have started this, continue to remove as much of it by hand and eventually the hornwort should outcompete it naturally, while cleaning the water for you too! This is a much better option than using barley straw - which would actually make the water worse.

 

[Ludwig Venter]

Thanks 3 fingers,.... I have a High volume pump available for the purpose.... Only problem is.... it sucks so "loudly"... that my inlet contraption implodes getting me back to square 1...... Any suggestions on how to keep my inlet flow controlled.....

 

[Truck]

Thanks 3 fingers,.... I have a High volume pump available for the purpose.... Only problem is.... it sucks so "loudly"... that my inlet contraption implodes getting me back to square 1...... Any suggestions on how to keep my inlet flow controlled.....

could you slow it down with some sponge as a some form of prefilter?

 

[three-fingers]

You can buy valves that can work as flow regulators.

But I don't think that would be too great for the pumps motor, and would reduce the turnover, which would make it less effective in combating algae.

Can you find a connector so you can use a larger diameter of hose? That would reduce suction, without reducing turnover and possibly putting strain on the motor .

Something like this (lying around or from an LFS in your area): [URL="http/www.cdaquatics.co.uk/catalog/aquatic-pond-hose-reducer-p-589.html"]http/www.cdaquatics.co.uk/catalog/aquati...ucer-p-589.html[/URL] Or DIY something .

 

[Ludwig Venter]

Right!!!... I've now submerged a pump in there with the inlet connected to a 5l bottle with the sump cut off (diameter of about 7") and wire mesh re-inforcement round the inner circumference, and it is covered with my wife's nylon stockings..... (all other attempts "imploded" the bottle)....... It is pumping out of the pond into a 44 Gallon drum & the overflow leads back into the pond. I'll let you know if this works!

 

[three-fingers]

Sounds good .

If the hornwort cant manage it, it's a good idea to put in some emergent growth in there too (like irises and water reeds) growing out the water.

 

[Ludwig Venter]

Sounds good .

If the hornwort cant manage it, it's a good idea to put in some emergent growth in there too (like irises and water reeds) growing out the water.

I already notice that there are clusters of this hairy stuff circulating around aimlessly in the pond..... Makes it easier to just scoop out.

 

[aaronnorth]

sorry i didnt reply, i have been away. I am going to have a look on the Barr Report, and have a talk to Tom, he might have measured the levels seeing as he has a CO2 analyser lol.