Newbie heat issue

More light = more yield.

I would use a silica supplement like protekt as it increases a plants threshold for heat stress. Grow smaller plants and more of them. You might have to change the light cycle to a less convenient time and use insulated ducting. It's a big issue.

FlashBabylon said:

Will it cause problems if I change the wattage on the dimmable ballast in accordance with the weather? For example we have just had a few days of hot weather, it is due to cool down again over the next few days. Would it be a good idea to up the wattage back to 600W while the weather is cool, or would this cause stress to the plants?

My reasoning is that the sun is not a constant brightness, some days it is hazier or cloudier than others. What do the RIU community say?

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It could cause problems with the bulb, shorting the life of the bulb if you dim it frequently. Otherwise you'd actually want to put a 400 watt bulb in to run it on 400 watts (and no higher).

As mentioned, it is better for the plants to just leave the light on full anyways unless it is too hot.

Thanks guys.

I understand the plants' need for max wattage, but I guess extra watts are no good if the plant can't photosynthesize due to the heat.

Weather is cooling down a bit now so I should be able to get away with 600W for the next few days. This weekend I will get to work on the shortening of ducts etc. I have insulated ducting on my exhaust btw.

Oh, and fewer, smaller plants is a bit of Captain Hindsight advice, stuck with what I've got now!

So - shouldn't cause too many problems to the *plants* to switch between 400 and 600 as weather depends? I appreciate it can shorten the bulb's life, but bulbs are not expensive.

As GrowinDad pointed out, the thing most likely to suffer will be the yield. Depending on # of plants, plant height and canopy spread: lower growth may die back and the buds on the bottom of the plant wont develop as much. If your solution is to keep it at 400, and the plants are tall (over 2-3 ft) you might consider trimming the lower most branches. The light from a 400 watt lamp doesn't penetrate as well as a 600 watt lamp.

A 400 watt lamp also gives off less lumen/watt than a 600 watt lamp, so less luminous efficacy although this isn't going to cause any tangible issues.

Some bulbs certainly can be expensive, and mutliplied by the # of lights you are running. I don't go for the Hortilux either, but I also don't buy the cheapest bulbs on the market. If I can afford it, I buy the Ushio Hi-Lux HPS lamps. I'll use that along with a slightly cheaper halide in bloom (together they provide a fuller spectrum).

The thing with these HID lamps is, while they all get pretty damn hot they don't all put out the same amount of lumens (or plant usable lumens) and they don't age the same. As HID lamps age (from use) they put out less usable light, but continue to give off a great deal of heat. You could check this with a light meter.

You didn't mention having an air-cooled reflector did you? If you don't, this is something I would consider, along with a decent high output inline duct fan. Also, aside from getting your ducting as short as possible, remove any unnecessary turns/bends in the ducting, and make sure you have the exhaust fan as close to the exhaust/end of the ducting as possible. Fundamental rule is, it is easier to pull air than to push it... same goes for water and string (try to push a piece of string).

FlashBabylon said:

I haven't found nutes to be cheap, but as someone tells me in another thread, I shouldn't have bought the PK and flower boost nutes that I have shelled out good money for

I also haven't found fans to be cheap. I'm looking at over $200 USD for a fan :S

It has to be quiet, more powerful than my current fan, and 5". Any suggestions what to go for? Currently using a Vents TT - the worst of the worst, it seems.... Had to wrap it in comforters to get anywhere near quiet running, and it's still too noisy for my liking.

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I'll be trying this:

I'm a cheap guy lol, and temps are usually not an issue for me cause I shut it down in the summer but i cut a hole in my reflector and mounted my intake to the top using a duct fitting (6" side take off), it worked quite well for controlling excess heat.