photoperiod

[poknsnok]

I have seen threads on photoperiods that say anywhere from 4 hrs to 10 hrs on the halides. I have a 7 ft tank 24" deep. i have 2x250 watt and 1 400 watt over the center. i have a thick glass brace over the center. I use the 400 to cut thru the glass.

actinis's on at 10 am and off at 10 pm
250's on at 11:30 and off at 8:30 (10 hrs)
400 on at 2:30 and off at 8 pm (5.5 hrs)

I believe the answer is "whatever works for you" but if i could get away with reduce the halide photoperiod i could save some money

 

[madmac]

This may not work for every single SPS in the tank. But I think your pH can clue you in. I've not seen a great deal written in forums so its anybody's guess as to whether it works.

If you have a pH monitor, chart out the levels over the course of the day, so long as it keeps going up keep it 'on', when it levels off(its reached photosaturation), then start reducing.

E.g.

My T5 lights come on at 7am, pH then is about 8.15... and it climbs
at 10.30 am, the single 250W MH comes on, pH still climbs
at 4.30 pm, the pH is about 8.50, the MH goes off
The T5s can hold the pH there till lights off at 7.30 pm

I'm experimenting with reducing the start of the MH, I'm backing it 1 hr later, so far it still reaches and levels at 8.5 at 4.30pm. Will monitor for growth and colour.