The octopot was what first got me on the SIP path. Just a few suggestions for when you start using one:
Get off of the big box store soils. I personally use a homemade peat/EWC/perlite mix with added amendments. The store bought super soils probably work, or with a little time and effort, you can make your own. Organic is the way to go with these systems.
Once you do your initial drench, leave top watering and the wet/dry cycles in the rear view. Top dress before you flip and after the stretch, but top watering can give you over watering issues. It's best to let the octopot do it's thing the way it's designed.
If it's possible for you... Dump the tap water. I use Crystal Geyser spring water from the grocery store. It's 99 cents per gallon. It takes 5 gallons to initially fill my two SIPs then one gallon top off per week each. Later in flower (when they really start sucking it up) it takes a bit more. Or, like Boo said, RO is a great option if you can do it.
I'm a huge fan of EM-1. It gives the soil some very good bennies and helps maintain your res. I add 1 tbsp of activated, expanded EM-1 per gallon of water. I've seen a few that use as much as 1/4 cup. There's a super easy recipe to make your own with rice, milk, water, and molasses. Plain water will work fine if you don't want to use EM.
I imagine you could use whatever soil you want to and feed with nutrients with good results. Imo tho, hempy buckets are more suited for that style than SIPs.