I JUST tore my 2 year old fluval spec V down last night! I LOVED that tank! (I'm moving to a 22g long) I had DHG in mine and it carpeted well with a Finnex FugeRay Planted+ 16-Inch on top. The DHG had about .75-1.25 inch of eco complete capped with .25 inch of flourite black sand (seachem) would imagine that .75-1.25 inch of ADA would be enough. Question 3 Cant help with as I have never used the dry start method. Question 4 Never once used any root tabs in 2 years but did dose ferts into the water column.
I will add that cutting DHG in a specV is a pain in the ass, the angles are annoying to work with a pair of shears but then again the level of annoyance does change with your scape. (DHG works in this tank just be aware when you are planting it how your going to trim I'll add a pic so you can see what i was referring to.) I'll be subbed to your post if you have anymore questions, its a cool little tank I'll be setting up again at some point!
P.S. I did have Co2 getting diffused then up the return pump via paintball co2 setup with solenoid
I will add that cutting DHG in a specV is a pain in the ass, the angles are annoying to work with a pair of shears but then again the level of annoyance does change with your scape. (DHG works in this tank just be aware when you are planting it how your going to trim I'll add a pic so you can see what i was referring to.) I'll be subbed to your post if you have anymore questions, its a cool little tank I'll be setting up again at some point!
P.S. I did have Co2 getting diffused then up the return pump via paintball co2 setup with solenoid