CO2 problem

[garcia]

Hi folks,

At the end of the photoperiod I measured a ph of 6 and kh of 5 giving me a whopping 150ppm of CO2. So my plants are not photosynthesizing?

Tank volume is 80 litres with 40 watts of PL light. My current fert regime consist of 1 PPM SO4 and 3ml of Easylife twice a week.

Could light could be the limiting factor here? If so, why is it surfacing only now that the tank's 4 mths old....never OD'ed on CO2 like this before.

Thank you.

[budak]

Your light level is a wee low for the tank volume.... if you could add another tube that might help.... try to achieve 2.5-3 WPG (use the AQ tank calculator for help).... your fert regime doesn't make sense to me.... do you know what exactly are you adding and why? I certainly don't. Try reading the "Articles on Dosing" on the Aquatic FAQ for some pointers. You could certainly try lowering your CO2 input to get the pH to a more sober level of 6.5-6.8, whilst maintaining your KH. Do you also use acidifying substrates like ADA Aquasoil?

[garcia]

I'm sorry....that should have been PO4. Hope that makes more sense.

I have a clay based substrate. Can't think of anything that's jacking up the ph.

[budak]

it doesn't make sense to just add PO4. what about NO3? Easylife covers just K and traces, if I am not wrong. Anyway, do read the dosing articles, esp. the one by Tom Barr for some guides.

You shoudl be using your CO2 system to control the pH level. if it's a pressurised cylinder, try reducing the Co2 feed such that you get a pH of 6.5-6.8..... if DIY, I am not sure how, but maybe adding less yeast may work.