Have you found a solid place to order the activated carbon for refills?
That's something I never wanted to mess with personally. I don't think you can ever pack them as good as the factory, they use a vibratory system that shakes the housing as the carbon is added and packed. I suppose you could do it but wow it will be a messy process. My filters are also pretty large (12" duct x 48" tall), it would be easier with a smaller one I suppose.
A big thing is cleaning the sock prefilter. Never eliminate it or dust will clog your carbon. I just use a shopvac to suck the outsides of my sock lol. I am afraid it wouldn't survive a wash plus I would have to take the fans off to slip the sock off. These filters are like a hundred pounds or something. lol
And also I didn’t realize the 35W was a standard for LED. That’s true watts?
35 watts as sent from the driver to the chips is the high end if you have good chips IMO. Generally thats like 98%+ efficiency at the driver. So if you have a 4x4 area then a light that draws about 560 watts would really rock that space. More chips driven softer is always best for efficiency and spread plus if you have a COB or strip fail the others can handle the added current without them all blowing. LM301B or H chips are pretty much the king right now. You definitely want dimming because you won't need the full wattage in veg. When designing or buying a LED it's important to know the distance you will be operating the light from the canopy, if height restrictions are in play you don't want a light that needs to be 30 inches away from the plants when you could build one that can be much closer. The Fluence Spydr 2i it's like 6 inches from canopy where a HLG 550 it's like 28 - 30 inches, each has it's ups and downs, gotta raise the 6" light more often. You can see that when you shop for lights, some are designed to be operated much closer than others. The guys in the LED section can really help you figure out the DIY as I am sure you probably already know. lol