red LED's
 

I have about 12 red CREE led's laying around, however I see all ready made units like Vega, mitra and such all have deep red.

would it hurt to put the CREE red on the tank with green LED's, or would this be a problem ?

Wouldn't hurt to give it more full spectrum but be careful cause the reds are really noticeable, I have 3 Cree reds in my 125 gallon LED setup and I'm not sure I would add anymore. But it does bring out the red in some corals

it is more in regards to using CREE led's at 620/630 NM or using deep red at 660 NM. this becouse I do have he CREE led's still in a package

the number of LED's I can add or reduce if needed

It probably doesn't help you out but after repeatedly fiddling with the output of my mitras I finally found a look I really like. I piggy-backed off a preset on the unit and maxed all the blue channels. The red and hyper red channels are actually both zero. Red purpled the look of the water column far too much. I'd say reds pop just a fraction less but I might be imagining it.

If possible I would temp wire a few up to see if you like the look. As stated above they really change the overall appearance even turned way down.