Freshwater to Marine Questions

Nope, completely different bacteria living in the sand.. if you converted over to SW with the same sand you would have a huge amount of die off of FW bacteria. On the other hand, if you can be patient and test accordingly, it actually may help get the cycle going in SW having the die off happen, still though, I wouldn't recommend it. Too much risk and unknowns for just a few dollars in sand.

Agree with Ace. However, you can take your current sand and wash it and then use it in the SW tank.

What I do is using a 5 gallon bucket, fill about halfway with sand. Wash the sand by sticking a hose in the bucket and mixing while letting the bucket overflow. Do this until the water is clear. Repeat with additional sand until all is clean.

Now you can use this sand in a saltwater tank…albeit not live for saltwater.

Yup.. but that isn't really an issue. Just put in a couple pieces of live rock during the cycle and you will get "live sand" by the time your cycle is complete. On top if the rinsing it out suggestion, I would then lay out a tarp or black trashbag under the sun and let the sand dry out for a couple days if it is possible. I know it is freezing cold in most places around the country and the moment so it may not be possible and is ok not to do that, but something I like to do if I reuse sand I got from someone else.

Sand isn't usually expensive though.. I paid $40 per 50lb bag of aragonite.. bought 4 bags of it for my 75G tank. Compared to the $15,000 I have now dumped into my tank in the last year, the $160 in sand was just a drop in the bucket.

ya, I definately have an addiction to my reef tank.. and forming a local reef club and getting "bit by the SPS bug" really added to my costs this last year. Before I got into SPS corals I would spend maybe $50 a month on corals and that is a high estimate... since going SPS I am now spending $400-$500 a month just on corals although my tank is now very full and thankfully since space has started to become an issue I think my $500 months are going to be behind me now.

ebay always has some good deals on protein skimmers just check whats there and do a comparison of what would be best for you and go from there.