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Discussion Starter · #1 ·
Hi gurus,

Question about my co2 level estimates… using API liquid tests and a drop checker

200l tank, in tank diffuser.
Off gassed ph (tank water 36hrs in a cup) = 8.2 approx.
Peak co2 ph (in tank) = 6.4
Big drop, isn’t it?
Ph first thing in the morning before lights and co2 = 7.6

DC lime coloured (perhaps more yellow) 2 hours into light period, stays there for the remaining.
DC green by morning, never blue unless I add new fluid, which I do every 2 weeks.

Fish completely fine, no evidence of distress.

KH is 9 both in tank and degassed.

Would you use the fish to determine this is all ok, or would you use the various charts to say this is too much co2?
 

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Discussion Starter · #3 ·
If fish is fine then its fine. Plants will happly take more.

You should consider flow and distribution of CO2 more then just plain CO2 levels. Also surface agitation and gas exchange.
Thanks MoreliaViridis, appreciate your response.

I am running a Sunsun 2000l/hr (reduced to roughly 1200l/hr with media). With surface and deeper angled spray bars. I also use a power head to push water through a suspected dead spot. I think flow is ok and perhaps why my fish aren’t affected?
 

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Discussion Starter · #5 ·
Your situation shows why you can't use the charts. With your KH the chart would indicate dangerous levels of co2. I have similar situation with Seiryu stone raising my KH.
Thanks Asteroid, that’s exactly what I was debating. I feel better about my co2 level now, I think.

I am going to change to an inline diffuser soon (once it arrives). My feeling is if the diffusion is more efficient when inline vs in tank, I should lower my injection rate a little and then reassess the ph drop.

Does that sound logical? Alternatively I could leave my needle valve as it is and see if my fish respond negatively to the change…
 

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Thanks Asteroid, that’s exactly what I was debating. I feel better about my co2 level now, I think.

I am going to change to an inline diffuser soon (once it arrives). My feeling is if the diffusion is more efficient when inline vs in tank, I should lower my injection rate a little and then reassess the ph drop.

Does that sound logical? Alternatively I could leave my needle valve as it is and see if my fish respond negatively to the change…
I think they'll be fine as long as there is decent surface agitation.
I know mine were.
 

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Thanks Asteroid, that’s exactly what I was debating. I feel better about my co2 level now, I think.

I am going to change to an inline diffuser soon (once it arrives). My feeling is if the diffusion is more efficient when inline vs in tank, I should lower my injection rate a little and then reassess the ph drop.

Does that sound logical? Alternatively I could leave my needle valve as it is and see if my fish respond negatively to the change…
If all is good I would just leave it. All co2 methods work. To me it's really preference, sometimes with the in-lines ones you get the soda effect to the tank, I generally don't get that with a regular diffuser. I don't worry about efficiency since the co2 is so cheap.
 

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Discussion Starter · #8 ·
Plant Green Pet supply Organism Terrestrial plant

Just thought I’d post a quick update. I did end up reducing my co2 just a smidge with the change to an inline diffuser as by the end of the photo period several of my fish were at the surface gasping… I may have panicked a little but with my ph drop so big I got worried.
I upped the ferts to closer to EI levels 2 weeks ago and my plants are really growing fast now. Tank is just under 4 months old since the rescape!
Thanks all!
 
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