[Myka]

You are very welcome!

I think you are still being rather exuberant with the amount of fish you want to put in the tank. It is not a freshwater tank where the fish population can be much greater without compromising the water quality.

That's cool your dad's a chemist! I would assume then, that he knows to calibrate it for alkaline pH rather than acidic pH. I am very surprised that your pH is that high. Are you using any additives at this point of just salt? What salt are you using?

Are you really amped on getting clownfish? They do much better in pairs, but you would be filling your tank almost to capacity just by getting a pair.

If you don't mind, I would like to suggest some of my favourite fish that I would consider suitable for a 20 gallon tank. I choose these fish because they have a small territory, and do well in nanos. Note that some are not compatible with eachother:

~ Yellowhead/Pearly Jawfish (proen to jumping, should have a lid on tank)
~ Clown Gobies
~ Yasha Goby (prone to jumping, pricey)
~ Firefish (prone to jumping)
~ Neon or Sharknose Goby
~ Hi-Fin Goby
~ Yellow Striped Cardinalfish
~ Yellow Watchman Goby
~ Orchid Dottyback
~ Yellow or Blue Assessor (pricey, can be a bit harder to obtain)

If you're really set on clowns, consider tank-bred True Percula Clowns (a bit more sensitive than Oscellaris to acclimate, but hardy once acclimated) or Barberi Clowns as both of these clowns will stay smaller than the rest.