Hi @Randomblame , I've ordered 4 QB 96s for my 4x4 and would like to know how many QB3s to install for the proper ratio of Far red light. Also what are your guidelines regarding timing and spacing the far reds for emerson effect and flower initiation? Thanks!
HLG QB 3s
- Thread starter GLV7
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Randomblame
Well-Known Member
Sorry for the delay, very busy currently.
For a 4x 4' area I would use around 15-20w of far-red. It's more than needed for end of day treatments but if you plan to use it as "booster" you need a little more. Each QB3 running at 700mA should have around 4,5w net and 5,5w at the wall so 4 of them would fit pretty well. This way you can use one QB3 per 2x 2' area which gives you a nice and even spread.
Good thing is the QB96's have already red and deepred added and together with a QB3 they will work hand and hand.
Far-red has other beneficial effects. It helps to warm up the leaves, it eliminates the overexcitation of PS system 2, it has a shortening effect on the flowering stage and it drives the emerson effect.
So even when you harvest up to a week earlier the final yield will be almost the same.
I would power them in series(4x ~6,5v) with an PLM-25-700(18-36v/700mA) and use a Sonoff Basic(5 bucks) as separate timer to switch them on and off when needed.
18w far-red net should be ~30μMol/s/m² ppfd inside a 4x 4' area which is a lot for EoD treatments. One need between 2000 and 4000μMols total for EoD treatments. 2000 you have already with only 66,6 seconds and to get 4000 it needs133,3. That means 1-2 minutes past light off is already enough to put them immediately in night mode. More than that can cause serious stretch so be careful. I start using it over the day when the stretch is almost done. EoD treatments I start when switching to 12/12h with a low dose of ~2000μMols and when the stretch is done I use the full 4000 until the end.
This way I've almost no additional stretch and the plants finish maybe 4" higher.
Play a bit with the timings, each strain has slightly different demands.
"Each QB3 running at 700mA should have around4,5w net and 5,5w at the wall so 4 of them would fit pretty well. This way you can use one QB3 per 2x 2' area which gives you a nice and even spread."
Wouldn't 1 QB 3 per 2x2 mean a total of 2 in a 4x4 is optimal? I'm going with 4 on an APC 25-700.
Thanks so much for the info!
Wouldn't 1 QB 3 per 2x2 mean a total of 2 in a 4x4 is optimal? I'm going with 4 on an APC 25-700.
Thanks so much for the info!
Randomblame
Well-Known Member
Nope, lol!
2x 2' = 4sft, 4x 4' = 16sft! 16 divided by 4 so its 4 times a 2x 2'. Draw a 4x 4' area and make a cross in the center, bro!
An APC-25-700 fits too its only a bit less efficient as the PLM(87 vs 84%) but we talk about 18-22w; 3% less means less like 1w difference. So both drivers would work and the APC would use ~1w more for the same amount of light.