That is why the only measurement I respect comes out of a PAR meter. Distance IMHO is nothing more than a shot in the dark. OTOH with the proper tool, you KNOW exactly what is going on.
OTOH, OP has a light, without the assistance of a user manual or a foot print for that matter, he is shooting in the dark so to speak.
A par meter does cost about 300-400 euros .I dont have that kind of money right now .Good observation
OTOH, even with a simple meter, he can measure the light intensity @ height X, and the changes (in intensity) when the other switches are selected. I will take an educated guess here (with this light) that switch one is active during the seedling phase, switch 1 & 2 for vegging, while all three closed for flowering.
When we look @ the recommended umol value for various stages, it is always a range, therefore is there really a need for a "precise" reading? Well yes if you are in a lab using a meter for light development etc... but such precision is not really necessary for growing cannabis, because you dial in your grow commensurate with "your" meter reading, raising or lowering your light accordingly.
When we see Mfrs recommending a distance lets say 18-24 inches. That is quite a spread. 400 umol with my setup and meter. So if Johnny's meter reads 390, is that really significant to us? Not really, as I dial in my light by clicks not inches:
My rationale behind owning one is quite simple. Why not eliminate "one" factor of the equation, considering all the other pitfalls of growing e.g nute deficiency, VPD, etc...
- cutting/seedlings ~ 100-200 umol;
- clones ~ 100-200 umol;
- Veg ~ 300-425 umol; and
- flower 700-1200 umol, with CO2 enrichment above 1K umol.
As stated you don't need to own a top of the line one. But unless you get a grip on what's going on with this grow... it is simply money down the drain.
Do you have a spesific one to suggest?
Paid $125 USD for mine (@ the time 2yrs ago)
