Calling All Experts! Lights!

Hello all,
I’m currently using a Sunsystem Yeildmaster hood with a 400 wttr Ultra Sun metal halide bulb for veg. 5x5x7’ tent. Is this enough light for 4 girls? The two Blue Dream seemed to do ok, but I’m wondering if they would have done even better with more light. I was looking at the AGROLED led light. The big one lol.

400w is fine for 4 plants. I use a 600w dimmable for 6 plants in 20" pots. I start at 250w for a couple weeks, turn it up to 400 until i start budding, then bud them with 600w.

Works for me


Sounds fine for what you’re doing. If you fill that 5x5 up though you’d want to go a little bigger. Like 600 watt veg and probably de 1000 for flower.


Just thought I would put my thoughts in… if it were me I would put a light above each plant if you can control the temp easily. I run 4 600w hps over 5 plants and get great results. Need to have a lot of air flow to keep temps down when the lights are on. But that’s just me. You do what works for you and try new things if you can.

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I also use very large pots (50ltr) and a recirculating water system. Just how we do it in aus. Also some mates of mine use a run to waste water system. I see in the states it’s done very differently. As it is highly illegal here we try and do less plants but bigger because you get done on how many plants you have.

Here I thought you were going to bust out tech info VA/SQ Ft and photosynthetic photon flux density. Ah well. Listen to @dbrn32 he got ya!


I did, in my head though. A typical 400 watt mh bulb is about 1 umol/joule. Everywhere you look will recommend a ppfd of about 400 for veg. But as long as you’re not in a red dominant spectrum quite a bit less will do fine. With a good fresh bulb you can veg a 4x4 pretty well with a 400. Stepping up to a 600 is a lot more efficient and a third more power. So with a decent reflector they do ok in a bigger space. Wouldn’t try flowering with it though, in a space that big even standard 1000 is on weaker end.

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Higher watt=Higher yield, I think you can add another light in tent 5x5. I am using 740W Mars Hydro light in tent 4x4, 46W/SF,plants are very bushy

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Mars hydro lights only pull about half the advertised wattage from the wall @Devile

I bet your closer to 25 watts/ft2

This is a mars hydro 720

However it pulls less than 300 watts from the wall when you look at the actual wattage

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I see in another thread that you have yourself covered and your not posting advertised wattage :+1:

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This is easily misunderstood. Higher light levels usually lead to bigger yields, and more watts doesn’t always mean more light. Then there’s always the other aspects of a grow that can be contributing factors as well.


There’s no doubt higher watts doesn’t mean a whole lot. The 400 watt DIY light I’m running has literally replaced 3 Amazon lights at 260 watts each. I think I may actually be burning the plants with too much light. Something I’ll have to learn about.

The Chinese lights didn’t make the leaves turn yellow until almost all pistils were red. For me higher watts was just more heat that I couldn’t get rid of without an extra $100 a month for turning the AC down.