I have both SW
Here are some of the key differences:
1.) biggest one is cost. SW
is probably 3 to 5 x as expensive for everything. Right down to the water
is much less forgiving on water quality. Rather than striving for nitrates below 40, you need nitrates below 5. Any chelated metals in the water will harm the fish and inverts. Reefs are very very sensitive to everything. Things you use intentionally in FW
to fertilize plants will harbor algaes and cyano
that will smother and kill your corals. Tap water is absolutely out of the question.
3.) Filtration. You can't use floss or biomedia in SW
. You want as much of the filtration as possible to come from your live rock, wet/dry sump and protien skimmer. You can't get away with cheap HOBs as much (you can ,but you will have to fight with your water quality a lot more).
4.) water movement. You have to have powerheads to move the water in your tank. No stagnant water or dead spaces, or as little as possible
5.) storage storage storage. You need big empty clean vats for storing fresh RO
water and mixing and storing SW
6.) Many small water changes as opposed to fewer large ones. You want to change water about 10% 2x a week rather than 50% once a week or two. Keeping nitrates and pollutants down is a big key
7.) lighting. unless you plan to go FOWLR
, you need intense, expensive lighting
8.) Feeding. Lots of target feeding
9.) stocking guidelines. You can have much fewer fish in SW
10.) testing water. takes more tests, and they are more expensive than the FW
11.) evaporation and top off. You have to keep your SG
in line. Evaporation brings it up. You need to add FW
regularly for evaporation not just for looks, but to keep your chemistry straight.
Those are just the ones I can think of off the top of my head.