Co2 and light timing

[Franks]

Yes I have a few Amano shrimp and harlequin, gourami and cardinals. All display no stress during Co2 injection. I'm now playing with surface agitation and may even play with running no wavemaker during lights - just the filter spraybar. At night, I'd run the wavemaker facing the surface.

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[Andy Thurston]

Some people might not agree with this but I'll tell you anyway. Your livestock will be a much better drop checker than any piece of manufactured equipment and the more different types of fish/shrimp that you have the better. Different critters respond differently to co2 levels at different times. ottos will get pink/red gills before the co2 reaches critical levels and glowlight tetras will loose their colour way before co2 reaches critical levels. I removed my drop checker from my tank because it was always yellow.

When I set a new tank up I have minimal surface movement. I inject co2 as quickly as possible until the livestock starts showing signs of discomfort/distress as soon as this happens I use my ph pen and take a reading, then I do a water change to bring the co2 to safe levels(I also increase surface movement/agitation at this time). This gives me an absolute maximum/minimum ph/co2 level that the livestock can handle. If the reading is 6.2 for example then when I set up my co2 levels then I aim for around 6.4-6.5 at lights on and throughout the photoperiod.

Have a read through my journal(it might not be the best scaped tank but the technical side of things are covered quite well) there are some good pictures of fish showing the early signs of co2 distress there is also a ph profile for the tank which will give you an idea of what you are aiming for although your ph and KH values will be different. I went through many problems with the tank and every change I made is documented there.
here is the link

http://www.ukaps.org/forum/threads/andys-60l-cube.31194/

any questions, feel free to ask

 

[Franks]

Thanks for the advice, I'll have a read through your journal.

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[Easternlethal]

I agree the best approach is actually to look at your fish to find out what is the real max Co2 your tank can hold. However it's not a good idea to reduce flow because that actually helps distribute Co2 around the tank. Without it the dissolved Co2 molecules will disperse upwards and out of the tank. some of course will eventually spread through diffusion but there's no reason to rely on that. I would also have some surface agitation because it will decrease the level of Co2 at the upper layers of the water column and the more sensitive fish can stay up there if they get uncomfortable. That way you can actually have more Co2 concentration in the lower layers of the water.

Re ph I do not measure either because that actually measures the presence of carbonic acid and is affected by the amount of kh in your tank. If your tank has high kh it will take a lot to drop the ph. Also I don't personally believe carbonic acid is an accurate indicator of the amount of dissolved Co2 in the tank (especially not in a tank with lots of flow under injection that is not in equilibrium).

 

[Daveslaney]

Not trying to fuel a fire or anything. Just looking for answers.
But will not higher surface agitation increase o2 levels? With higher o2 levels can you not run higher co2 levels without distressing your livestock?
Is this why wet dry filters in sumps work so well and allow higher co2 levels to be run? O2 must be high with this filtration method
If ph pens and drop checkers work on ph readings to monitor co2 levels. Why is a ph controller a unreliable way to regulate your co2 levels?

 

[Easternlethal]

higher o2 doesn't mean you can have more co2. they are independent. and o2 should be coming from the plants really. not through the surface.
my post above explains why ph is not a good measure of actual co2. a ph controller has the same issue.

 

[Daveslaney]

Ok thanks.
When I first started running co2 injection all my returns where underwater so little or no surface agitation. If I pushed co2 levels and my drop checker went into the yellow my fish would be at the surface.
Now I run the spray bar method so lots of surface agitation so higher o2 levels? Now my drop checker will go into the yellow if I push co2 levels with no apparent distress to my fish. Even though both are independent it suggests to me higher o2 allows higher co2 levels?

 

[Franks]

I think I'm at the point where I've reached a safe max. DC is green/yellow tinted, I'm dropping around 1.2 PH and I've a large spraybar and wavemaker running. No distress to fish whatsoever and all plants apart for my shaded anubus pearl nicely when in the last quarter of the photoperiod.

I think a trip to The Abyss is in order for some more Amano to help munch the slight BBA I get on the wood.

Cheers guys

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[Andy Thurston]

However it's not a good idea to reduce flow because that actually helps distribute Co2 around the tank

please re read my posts. I was not recommending that the op reduced their flow. I was recommending that the op reduced the surface aggitation to keep more co2 in the tank to obtain a maximum co2 level for their livestock

 

[Andy Thurston]

Even though both are independent it suggests to me higher o2 allows higher co2 levels?

I believe that this is true too. I also believe that you need to maximize co2 and o2 levels when injecting co2 into your planted aquarium.

I also believe that you should maximize co2 levels without distressing your livestock. if any of your fish have gills that are redder than normal or start gasping at the surface then you should aim for less co2 in your tank (higher Ph). Then if your plants are still suffering then you should consider lowering your lighting levels

 

[Easternlethal]

I was not recommending that the op reduced their flow.

I didn't say you did. I was responding to the OP's point about cutting the wavemaker during the day.

I'm dropping around 1.2 PH... No distress to fish whatsoever and all plants

This supports my point that you can have low ph due to high carbonic acid but dissolved co2 is also actually lower than what would be assumed under equilibrium conditions. This is why many aquarists have said that Co2 is frequently lower than what a yellow dropchecker would suggest.

Even though both are independent it suggests to me higher o2 allows higher co2 levels?

Respiration is not just about getting o2 into the respiratory system but also getting co2 out of the respiratory system. When co2 is high, it makes it difficult for fish gills to remove co2. O2 does not help that. When co2 is increased but so is surface agitation and flow and fish seem unaffected what is happening is that the co2 is being distributed more efficiently and escaping at a faster rate in such a way that the concentration of dissolved co2 actually does not rise overall. And this environment helps plants.

 

[X3NiTH]

For 30ppm CO₂ (or thereabouts) drop checker colour states can differ depending on which pH indicating fluid is used, if we stick to Bromothymol Blue, this I have found comes in two flavours, Protonated and De-Protonated. One is an acid the other is alkaline. One fluid will appear red in the bottle but is actually stains yellow (a bit like saffron), the other fluid will be a dark blue in the bottle and will stain a lighter blue.

The two Drop Checkers on the left below were pulled from a CO₂ injected tank and immediately photographed before any colour change could happen at the gas transfer interface.



Same reference 4dKH fluid is used for all checkers, the Yellow reading DC on the immediate left is the Protonated Yellow checker fluid, the one to its immediate right is the De-Protonated checker fluid. The DC on the far right is Protonated checker fluid after going into the reference fluid and not exposed to injected CO₂ in the tank.

It is what it is. I was confused and surprised by this and had to go and read up on indicator fluids a little, thats when I found out Bromo exists in the two flavours. They nearly match in indication but the Protonated form turns yellow earlier under the same concentration of CO₂ than the De-Protonated form does.

If you have yellow type DC fluid aim for a Yellow DC for 30ppm (or thereabouts), unfortunately on its own there's no way to indicate if the CO₂ is more than 30ppm and climbing unless you have fish to tell you by heading for the surface to breathe.

If you have the blue type fluid you want it to turn the above shade of green to show 30ppm, if it turns yellow it's more than 30ppm (from experience fish will be at the surface above this level of CO₂, different story though if the plants are having a good day and they are pearling due to photosynthesis).

 

[Daveslaney]

Ok thanks.

 

[herezor]

I would keep surface agitation high and increase CO2 injection. To do that, I have suggested this in a couple of threads, I would buy a cheap permanent pH meter which you can find for 30-40 euros and I would aim for 1 unit pH drop from CO2 on to lights on. Normally you can achieve that with a inline atomizer in 1-2h.

DC, CO2/KH table, bubble counters etc are, in my experience, useless and I must admit I have used all of them in the past.

Just my two cents.