Currently have the light at 22 inches above the po...

My guess: download Photone, google "cannabis DLI" and just adjust so it fits the current stage of growth. it's the easiest by far and you will develop an actual feeling for it instead of "well in this stage the lamp needs to be raised by 20cm on 80% power" Also i go for DLI and not ppfd

Most manufacturers light recommendations are very inaccurate and often over powered. Plants don't need a lot of light in veg, save the power for flower. I use to move my lights and would be around 30" and 40% intensity during veg, this would go to 24" during flower and I raise intensity each week until middle of flower where I run it the hardest and then toward harvest I start lowering intensity again. In my current 8x4 grow, I decided to leave the lights at the top of the tent and just adjust intensity as they grow, saves a lot of time not having to move 3 lights. Doing it this way, as seedlings my lights were almost 6' over the plants so my light was set to 70%. The higher intensity also raised temps and seedlings like to be warm. When the plants grew taller and I transplanted into bigger pots, the plants were now closer to the light and I lowered intensity to 60% and as they grew closer, 50%. They will stay there until flower. Coverage will always be the best at the highest point as well, the closer the light is to the plant the less area it will cover.

depends on hours of operation and area you need to cover. lower wattage, less area covered and you can get it nice and close for small plants, like seedlings. Higher up will improve area of coverage and may make light more balanced across canopy, but if growing photoperiods, need to always plan for needs relative to 12hours of operation. If you need more than 67% power over 18hours, you will be lacking light over 12 hours if using that same light. no matter what 'they' say, simply react to how the plant is growing. stretch = more; too tight = less. Temp and humidity will impact that, you so you may get different results in different seasons depending on climate control. I find sprouts need roughly full light within 24-48 hours or i get excess stretch. so i give them what they ask for.

How do you know its accurate unless you have a real light meter to compare it to? and if you do have that, why are you not using it? The phone apps are not quantum sensors, they can not do PPFD accurately. its a calculation based off of lux on a camera lens that is not a designed light meter. They can sometimes get pretty close but they first need to be calibrated for accuracy, you need a real light meter in order to do that. I have installed it on 3 devices before. the readings where off by as much as 300PPFD when comparing them all at the same height and location in the tent. It gets even more wacky if your LED light is not using a full spectrum led. A lot of them are all so similar it can work out well. But if its blue/purple/pink. nah just forget it. Most lights I have seen keep the hang height about the same and then alter the dim settings. something like 20-40% seedling, 40-60% veg and 100% flower. The hang height is about how the lights is distributed, less hot/cold spots. But base your lights height and dim on how the plant grows. to much stretch. more light/intensity. plant is too compact less light/intensity. follow the guide from your manafacture its lilkey good.