Dose before or after lights out?

[b4tn]

Does it matter?

 

[travis simonson]

Great question. This sounds like a good one for the more experienced botanists here on AA. I dose right after lights-on in the morning. My assumption (and it could be completely wrong, but I'm going to do some research) is that plants assimilate nutrients more heavily during the oxidation/daylight side of the redox reaction. I believe the uptake of phosphorous occurs during this period (someone please correct me if I'm wrong here) and my guess is that other nutrients are also consumed more heavily from the water column during daylight hours. So, operating on these possibly completely incorrect assumptions, I dose first thing in the morning in the belief that I'm providing the plants the nutrients they need during the period when they will most heavily utilize them.

 

[Tiffi]

I think unless you're adding short-living ferts (trace) it shouldn't matter. The ferts will still be in there the next morning, when the light comes back on. Otherwise during the day, when the light is on would be better IMO, since the plants do photosynthesis and use the ferts.

 

[czcz]

I dose both macros and micros during my main tank's photoperiod because it makes the most sense to me. I've run a 24 hour light cycle (reverse photoperiod fuge) and saw no difference with Fe, and used plants as indicators of in both tanks (P. stellata "fine leaf" in main, Wisteria in fuge), for what it's worth. I think as long as macros don't bottom out and Fe is dosed regularly it's not critical when they're dosed, but have also found mimicing Travis's methods never hurts

I believe the uptake of phosphorous occurs during this period (someone please correct me if I'm wrong here) and my guess is that other nutrients are also consumed more heavily from the water column during daylight hours.

Travis, you may find it interesting that I get quick pearling whenever I dose KH2PO4 during any time of the photoperiod (first and last half-hour excluded). Since I'm no chem wiz, I asked if the H2 had something to do with it. Here's Tom Barr's response:

No, when a PO4 limited tank is relieved of the PO4 deficicency, the PO4 allows the Chloroplast to really produce lots of O2, ATP and NADPH.

This can be seen in about 40 minutes or less with slow movement in the tank's current.

Regards,
Tom Barr

My system is not limited in PO4 (~3ppm) but find this interesting all the same, and it sent me off searching for answers way over my head Hope it helps.