Do my KH/pH levels show enough CO2?

[jac_france]

Hello everyone.

I’m hoping for some clarity on CO2 (groan) because I’ve been reading up on it so much as I’m upgrading my tank, and can’t find an answer to the question I have, which is… do I really need it if the water in my aquarium sits naturally at pH6.8 and KH5.5, as it has done for nearly 10 months or so. From looking up these figures on the CO2 tables, that gives a result around 24 – so do I need to add any more CO2?

Currently in my 20-litre nano, the substrate is JBL Aquabasis+, with JBL Manado on top. 50% water changes every 10 days, Dennerle 11w light. Fairly heavily planted with plants and moss. They don’t produce bubbles, but my pogostemon helferi is hardly a low-lying rosette – it’s about to pop out of the aquarium. My plant book says it needs 20-30 mg/l of co2 to do well. But then again it also says it grows to c. 10cm and mine is nearly double that.

The larger, 43-litre aquarium will have a similar set-up as regards substrate, rocks, some of the same plants (cuttings from the pogostemon h. for a start). Lighting is a Solar Lux 26W, White 6500K. So I’m expecting the water parameters to be similar.

The question arises because I want a carpeting plant like eleocharis parvula or acicularis, and everyone suggests successful carpeting growth comes only with a CO2 system. I don’t want to spend on a CO2 system unnecessarily, but then again I don’t want to waste money on a carpet plant that stands little chance without one.

[FONT=&quot]My neons and shrimp, who have been eyeing up the larger but still waterless tank sitting next to them, would be very grateful to anyone who could advise on whether I actually might have an okay supply of CO2, or whether I’m just kidding myself.

Thank you, thank you.
Jac



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[schoeplein]

CO2 is constantly going towards equilibrium with the outside air. Just because your KH and pH are at a certain level doesn't necessarily mean there's an increased amount of carbon dioxide in your water. And even still, it would reach equilibrium with the outside air fairly quickly after changing the water.

If your plants are growing, all is good. If you amped up your lighting, or had plants that weren't growing, then we could discuss carbon dosing, or if you'd need any other supplemental elements.

Sent from my SM-T310 using Aquarium Advice mobile app

 

[Sk3lly]

I think the reason your pogostemon helfuri is growing up so high is its searching for light. Your lighting probably isnt good enough to make it stay low.
Pressurised co2 is only really 'needed' in high light tanks

 

[jac_france]

Thank you both

Thank you Schoeplein and Sk3lly for your replies.

I can see now that having those readings doesn't by default mean that the given level of CO2 when you cross-check them against the CO2 tables, is actually there.

And Sk3lly yes, having now taken some of the pogostemon h. out of the tank to start the process of transplanting it to the next, I can see that it's actually grown sideways! There are lots of big rosettes all the way along, with roots growing out of the side - it needs pushing down into the substrate all along its length (no room to do that in my nano as there isn't the space for all the new rosettes). Doh.

I think I will give the eleocharis a go in the new aquarium - as I think it might grow, but not brilliantly quickly. I can then look at introducing CO2 (and everything that entails) if need be, using I think the sodastream CO2 method that I've been researching. After the initial outlay, the refill sodastream gas cost should only be 13 euros every 3-5 months.

Yay... thanks again both of you for replying - I imagine my next research project will be: lighting !!!!

Jac

 

[aqua_chem]

If you're not adding CO2, then no, you likely don't have that level of CO2. The KH/pH/CO2 calculations are done using a series of ideal assumptions, namely that your have no other acids/bases in the tank, which we know is not true. If you have wood or a highly stocked tank, it can essentially be thrown out the window.

The best way to measure CO2 is with a drop checker. Alternatively, the CO2/pH/KH system can be used somewhat by measuring pH in the morning before your CO2 comes on (assuming a pressurized system) and then several hours into your light period. A change of ~1 pH usually shows good CO2, although that's a pretty vague measurement.

 

[jac_france]

Thank you Aqua_Chem.

I think I should definitely add a drop checker to my list of requirements if (perhaps more likely 'when') I go down the pressurised CO2 route. I've invested a lot of time and effort into research for this next, bigger project - and I want to give it as good a shot as budget permits.

As my dad often says, not worth spoiling the ship for a ha'porth of tar.