Starting a 20gal

[gqlmao]

By saying 4 inches he is thinking about growing more nitrifying bacteria and other goodies, I would say 4 inches is still too shallow 6-8 inches would be your best bet at dsb. However, You do not necessarily have to have sand bare bottom tanks are fine. The flow he might be quite right because a K1 isn't very strong, I'm running a K3 and its really weak in my opinion, 2 power heads might be a good choice. Its all good you can add more flow in the long run. The rio pump should be fine for you if its lightly stock, however I have no experience with them. Remora's are alright however I heard they aren't all that great either due to its weak pump. For the salt thats up to how much water changes you make. Lower buffering means that you would have to add supplements such as baking soda for example. I've used IO for 3 years with tap water and I got no problems but its Calgary here. Just get some buffering agents at your lfs they should be around 15 bucks and will last you for a long time to come.

Don't get discouraged cause people have to learn from experience and plus you haven't tried your set up yet. Don't let people tell you what is right and wrong cause they might think they know everything about reefing, the fact is that they do not. No one does.