CO2 levels after trimming

[Ruskie]

So today I’ve had what I would probably call my first mistake/ close call with CO2 levels in my new tank.

Tank was dark started and has now been planted for a month. Today was the first big maintenance session other than the weekly water changes and pre filter clean. All pipework cleaned, diffuser cleaned and quite a big trim of stems and carpet. Put everything back and kicked back for food and beers.
A few hours later and I noticed one or two of the fish appeared to be going to the surface but I thought they were just playing. 20 or 30 mins later and all the fish were at the surface and I knew things weren’t right.
Thankfully I caught everything in time. Switched the gas off and did another big water change and all is well.

Its now painfully obvious to me that the hacking of plants and decrease in plant volume is the reason for my levels being out of kilter. From what I’ve read with CO2 you can pretty much set and forget once your levels are good, not strictly true is it! Fish were getting gassed 2 hours before the end of the normal period. All part of the learning curve I guess but it’s raised a couple of questions I’m hoping experienced users can chip in with how they go about things.

1. On big maintenance/ pruning days do you just leave the gas off for the day?
2. Will the plants recover quick enough to leave levels as they are or do I need to dial it back?
3. If dialling back how quickly do you increase levels again? Yes, I’m scared of algae 😀
4. Anything other tips worth mentioning?

Thanks for any contributions.

 

[bazz]

Hi,
I'm no expert but I would imagine this becomes more of a problem the smaller the tank volume but the simple way round it is to just trim one or two plant species per week (depending on size of the tank) rather than decimating all of the plants in one foul swoop. This has always worked for me in the past without having to touch the CO2 although I now no longer have stem plants and as such, no problem.
Cheers!

 

[Scaperinc]

I am not an expert but surely changing in co2 can cause fluctuations and cause issues , i think better thing to do would be to increase surface movement to create more gaseous exchange and if available aerate with a airstone or raised lily pipes

 

[Ruskie]

Hi,
I'm no expert but I would imagine this becomes more of a problem the smaller the tank volume but the simple way round it is to just trim one or two plant species per week (depending on size of the tank) rather than decimating all of the plants in one foul swoop. This has always worked for me in the past without having to touch the CO2 although I now no longer have stem plants and as such, no problem.
Cheers!

Tank is 100L. Everything was planted from 1-2 grow pots a month ago and was just left until well rooted before this big trim. Trimming one or two species a week does make sense and going forward that’s something I could probably implement. The carpet etc is not going to need trimming as often as the stems.

I am not an expert but surely changing in co2 can cause fluctuations and cause issues , i think better thing to do would be to increase surface movement to create more gaseous exchange and if available aerate with a airstone or raised lily pipes

And that’s what worries me, the fluctuations causing issues! That’s why I’m asking.

Fish have been perfectly fine for 2 weeks prior to the pruning session. The 50% water change I did after pruning helps with oxygenated water and the gas wasn’t wasn’t even on for the first few hours of the normal period but fish were struggling before the end of the normal period.

 

[Ruskie]

Is there any school of thought that cleaning the diffuser has it working better than it was out of the box when installed and I’ve been injecting too much all along?

 

[Scaperinc]

Can you post a picture of your tank please

 

[Ruskie]

Taken about a week or so ago. Pre trim obviously.

 

[Tim Harrison]

1. On big maintenance/ pruning days do you just leave the gas off for the day?
2. Will the plants recover quick enough to leave levels as they are or do I need to dial it back?
3. If dialling back how quickly do you increase levels again? Yes, I’m scared of algae 😀
4. Anything other tips worth mentioning?

I've always left the gas well alone, even after heavy trimming. If it's dialled in correctly to start with there is usually no need to mess with it further. In fact I try to time maintenance and trimming so it's done before the gas comes on. However, as plant biomass increases it sometimes needs a tweak.

Is there any school of thought that cleaning the diffuser has it working better than it was out of the box when installed and I’ve been injecting too much all along?

Quite often inline diffusers need a 30min soak in bleach before they're used for the first time. Manufacturing residue can block up the pores in the ceramic tube. 1:1 bleach and water is recommended. But I've used neat bleach before. I've found the best type is limescale bleach. It removes organics and limescale. Steradent tablets are also a good option.

So a clogged diffuser might have been the source of your problem. After it was cleaned it became more efficient and allowed greater gas flow.

 

[Ruskie]

I've always left the gas well alone, even after heavy pruning. If it's dialled in correctly to start with, there is usually no need to mess with it further. In fact I try to time maintenance and trimming so it's done before the gas comes on. However, as plant biomass increases it sometimes needs a tweak.


Quite often inline diffusers need a 30min soak in bleach before they're used for the first time. Manufacturing residue can block up the pores in the ceramic tube. 1:1 bleach and water is recommended. But I've used neat bleach before. I've found the best type is limescale bleach. It removes organics and and limescale. Steradent tablets are also a good option.

So a clogged diffuser might have been the source of your problem. After it was cleaned it became more efficient and allowed greater gas flow.

Interesting, I didn’t know about cleaning the diffuser before use! That would explain a lot of things!
I often read about people settling on or around 1 or 2 bps ish. When I initially set it up I’m at around 5 or 6 bps!

When I cleaned it yesterday I left it running and dumped it in a 50/50 bleach mix for about 30 mins before moving it into a clean water jug with Prime added for a further 30 mins.

Gas is due to turn on very shortly, I’d better dial it back a bit I guess!

 

[Zeus.]

I think @Tim Harrison has hit the nail on the head with cleaning the diffissor. I did big trim in my 500L tank and never had an issue, even when I was doing a 1.4pH drop. I did have turnover well above x 10 ratio which helps.
If anything trimming the plants should increase turnover which helps stabilise the [CO2] IMO/IME, yes there's less plant mass for CO2 uptake, but how much is the CO2 uptake by plants compare to the CO2 that just gases off - I bet not much id taken up by the plants and most of it is losted.