taking water samples

[thio]

may I ask: when is it appropriate to take readings from our tanks? with the lights and Co2 switch on or when the tanks are in darkness?
thanks

[pipsqueak]

I havent done so myself, but I believe they do so just before they turn off their lights at night, cause thats when everything is at its peak, and in the morning, just before the lights are turned on. Can't really explain more cause I'm not sure myself, but there's alot of info on this online.

[vinz]

Depends on what you want to measure.

E.g.:
1. Peak CO2 levels, measure at or just after lights off.
2. Fe consumption, measure before dosing, and note how much you dose. After a day or a few, measure again.

Got the idea?

[bigjohnstud]

----------------
On 4/4/2003 3:44:23 PM

Depends on what you want to measure.

E.g.:
1. Peak CO2 levels, measure at or just after lights off.
2. Fe consumption, measure before dosing, and note how much you dose. After a day or a few, measure again.

Got the idea?
----------------

Hi vinz, shouldn't peak CO2 be measured just before lights on? That's when CO2 that has not been consumed by the plants for photosynthesis is at the highest? Correct me if Im wrong.

Cheers

[PeterGwee]

That depends on whether you "off" your CO2 supply or not during the non-lighting periods. If you "on" your CO2 during the non-lighting periods..for example night time, the CO2 concentration will build up along with some input from fish and plant respiration and hence max CO2 level before lights "on". If you "off" CO2 during the night or lights off period, the excess CO2 will slowly escape to the atmosphere and reach an equilibrium of 2-3ppm of CO2 even though plants and fish contribute some CO2 through respiration (not significate).

[thio]

thanks. Would it mean pH & KH are best taken either just before or after lights off? This is to determine peak Co2 levels.

[vinz]

Actually, the answer is in Peter's reply.

It depends on whether you turn off the CO2 when the lights go out.

If you turn off the CO2 when the lights go out, the CO2 in your water will escape into the air thru the night until you turn on your CO2 again.

If you don't turn off the CO2, when the lights go off, the plants will stop consuming CO2 and hence the CO2 levels will rise. This will go on until the lights come on again and the plants start to photosynthesise and consume CO2.

Think you can figure it out?