Would it be a waste of time and effort to alternate between 400 mh and 400 hps every other week (or so)? I can't afford another reflector and ballast and I certainly could not manage the heat of 2x400w, but I've been reading about mh during flowering may increase potency (and decrease yield).

thank you

Welcome to the site, eachnewhour!

I am no expert, so i have never tried it and have never heard of doing this. Common practice is to use MH during veg and HPS during flowering.

start off with mh for vegg, and as your plants get bigger and you goto 12/12, use hps or even better both, ive herd you can use mh whilst flowering with hps.
but if your only wanting to use only one lite. id go with the hps all the way.id say dont be swaping all the time, it may mess with the plants cycle.

keep us posted if you end up experimenting with that. althought it is typical as email said, to veg with mh and flower with HPS.

theres no harm in trying and we can all learn from someone elses trials!

I know that common practice is mh for veg and hps for flowering, I was merely thinking of experimenting a little after I read about how mh during flowering may increase the amount of crystals, especially on sativas. Some people are reporting a substantial difference (a much more "up" high).

Next grow (C99) I will give them some mh during flowering, but mostly hps. Maybe a 2:1 ratio, or so. 5 days with hps, 2 days with mh. And I will keep you posted, but if anyone have anything to say about this, I'm all eyes.

thanks!

go for it man.

i think ill give it a shot too on a small crop. im about to start flowering now, but its a crop of Ice and i really want to see my turn out with my regular practices. i have some seedlings in soil that are still young, so a couple weeks ill get on this.

keep us posted and ill do the same once the next crop gets rolling.

ill be testing it out on a soil crop of blueberry. seeds are "guaranteed female".....we'll see about that...

That's cool - experimentation is important. You could also try using both kinds of lights for the duration of the grow (that's what i do - i use a dual-spectrum).

i just saw on another thread, that a first time indoor guy found a 2in1 swtichable ballast (works with both hps and mh), which would make this experiment really easy. i asked him to post the link, once i get it ill put in on here.