Cfm

[Vlad (the impala)]

My experience of them was not a happy one! - without filtration, two would cool 3x70w hps - just! - the "left over" suck was not enough to ensure an adequate airflow over the plants, or to overcome the most minimal filter - all this is achieved at peak revs - despite several attempts to mount them in a way the vibrations wouldn't transmit to the structure - it does, and they are loud! (even buried in the bowels of the cupboard). Mark 2 was so much simpler - one Soler & Palau tdi60 fan - (£50) sucking through homemeade carbon filter - almost silent! - (have to stick my head under the lights to hear it - it keeps 2 enviros and the cupboard cool, just running on the slow speed setting (its a 2 speed fan) - lots of airflow over the ladies......bags in reserve for the hot weather B)

seriously, by the time they add all the extras, those bloody pooter fans work out about £14 a throw, then the speed controller, another £15 - you've bloody near spent £50! -then you've got to source a 12v psu or similar

I reckon if growshop owners were honest, they'd sell you the biggest fan they could - it'll do your grow more good than any other single component! - thinks stiff breeze, not sargasso doldrums!

[40oz]

thanx i dont know what id do without this website

40oz

[40oz]

does any one have any wattage information about the s&p or lti fans or a list of the amount of juice they each soak up because im rather worried abot the leccy, ive been told that fans use a hell of a lot of electricity

40oz

[oldtimer1]

I will try and explain the reason for ventilation again.

Most of a plant is created/made from carbon dioxide Co2, a gas mixed in the air, the natural level is about 330 to 340 ppm.

Chlorophyll the green material in the leaf is the bio-lab where light, water and carbon dioxide are combined to produce a simple sugar called glucose. This sugar is the fuel for every plant process and also forms the basis of the plant compounds we are striving to produce. 95 to 98% of the dry weight of a plant is made by photosynthesis, while just 2 to 5% involves soil minerals, cannabis bud is round 2 to 3%, i.e. when you burn an ounce of organic dry bud, the ash that remained would weigh just 0.7 grams, this residue would consist of potassium, calcium, phosphorus and other soil minerals.

This means that the remaining 27.65 grams were made from the Co2 the leaves took from the air.

As the Co2 in the air around the plants drops below 330ppm photosynthesis slows! At about 200ppm it virtually stops, this mean the plant is not growing at all.

Rooms in most modern houses have a complete air change every 3 to 5 hrs. A grow box in a room like this, drawing air from the room and discharging back to the room will soon bring the Co2 of both the grow box and the room below 200ppm.

This means you may only get the equivalent of 2 or 3 hours growth for every 12 hrs you have the light on. The more light you have the more Co2 is needed.

If the Co2 levels get below 100ppm the plants metabolism also starts to shut down, the amount of water the plant can pump slows, parts of the plant can over heat, leaf damage can occur and finally the plant will wilt.

Why do people not think about this? Its not complicated. They will spend money on a bigger light, special nutrients, but the thing that the plants are mainly made of gets ignored.

For plants to grow at the rate they should they need constant fresh air.

With smaller lights this means a complete change of air in the grow box every 5 minutes. If the air is changed at this rate, the discharge air extracted will never be more than a few degrees above the fresh air being drawn in.

As I said the reason for extraction is not to reduce heat. But if the exchange is at the correct rate to supply the plants with the Co2 they need then the grow box will never even get warm.

With any light above a 250w 20 complete air changes or more is better ie at least one every 3 minutes.

[Vlad (the impala)]

Dear oh dear, I'd shoot that advisor if I were you - in comparison to lights, fans use bugger all electricity! From memory, my td160 draws less than 40w! (less than half the average light bulb!) And before you run away with the idea that the sort of current you'll be drawing for a small grow is going to be noticed, or frantically expensive - that's a myth too! (I once worked out a 250w burns about one and a half p an hour!) In contrast, immersion heaters draw simply vast quantities of power, as do cookers, fires etc.etc

[oldtimer1]

I think its 35w on full speed so it would cost £3.53p for ten weeks continuous running at 6p a unit.

40oz you had 5 topics about the same thing fans! I have merged them into one topic/thread.