I can't help you with anything regarding the sea.
But regarding the reverse osmosis system, it's better to contact here; the prices are much lower.
Brian6895
1. Membrane 100G.
2. Being calculated.
3. Good foam.
4. Not necessary.
5. Yes.
6. A total of 40 kg. The more J.K. (live stones), the better the cost ratio. You can buy it both from A and at Ai-Rife.
7. ................
8. None. The livestock settles in a couple of months.
9.
10. Yes, and drilling it yourself is not a problem.
11. One.
12. It is not needed.
13. Very critical. But the LEDs will heat less.
...............
P.S. All this information is available on the forum; my response is full of links.
Amber
If you are only interested in the cost of the conversion, consider a reasonable $10 per liter (it will be more expensive with LEDs! $10-15 per liter is a guideline with LL lighting) minus the cost of the aquarium (I don't think anything else from freshwater will migrate to saltwater).
The cost of converting a freshwater aquarium to a marine aquarium of 380 liters.