Freshwater to saltwater tank.

[Fishbros]

I have a 36-gal bow front tank that has been running freshwater for over a year.  I moved all the fish I had in there to a larger tank and want to convert this one into a saltwater tank.  I know I am going to have to cycle and change things.  I am making the assumption that the beneficial bacteria is a different type since it will have to thrive in saltwater vs fresh.  Does anyone have any tips or advice on this transition? I have heard I also need to get rid of the substrate that I have in there too, which I thought was odd but I am up for it.  Any advice is welcome.  I am doing FWLR tank so no reefs or anything too complicated right now. 

[AllFishNoBrakes]

To the best of my understanding the beneficial bacteria for salt vs. fresh are completely different, so you will essentially be starting over. If I was to start over and do salt, I would do just that; start over. All substrate and everything would come out, I’d switch to sand, I’d get rock work intended for a saltwater tank, and I’d mix up and add in my saltwater. Add a pump/wavemaker, cycle, and then start playing with saltwater fish.
 

Considering it’s a FOWLR tank whatever light you have should suffice, at least to start, but I have no clue if things like  coralline algae require different light spectrums to grow. 

Edited March 16, 2023 by AllFishNoBrakes

[nabokovfan87]

On 3/15/2023 at 8:36 PM, Fishbros said:

Does anyone have any tips or advice on this transition?

Salt will do a lot of the work for you. I would start with normal aquarium salt before you do anything and just let it run for a week with all the equipment to sanitize stuff.

This also gives you the chance to test and run everything you'd like to add, verify your setup, then do your water changes and rinse the tank and fill it up to start cycling.

I once emailed caribsea asking if I could take sand from my freshwater tank and use it for salt. Of course they said no, probably a bit of confusion on what I was trying to ask, but yeah.... Dry things out, the nice the is that stuff that lives in. Freshwater usually can't handle salinity.

On 3/15/2023 at 8:40 PM, AllFishNoBrakes said:

Considering it’s a FOWLR tank whatever light you have should suffice, at least to start, but I have no clue if things like  coralline algae require different light spectrums to grow. 

Are you going to use the BRS talk (see video/talk on cycling a tank that he did) which basically is about conditioning the rock and such in a trashcan for a while as a method to let it cycle in a very controlled way and encourage specific things?

Edited March 16, 2023 by nabokovfan87

[DiscusLover]

On 3/15/2023 at 8:36 PM, Fishbros said:

I have a 36-gal bow front tank that has been running freshwater for over a year.  I moved all the fish I had in there to a larger tank and want to convert this one into a saltwater tank.  I know I am going to have to cycle and change things.  I am making the assumption that the beneficial bacteria is a different type since it will have to thrive in saltwater vs fresh.  Does anyone have any tips or advice on this transition? I have heard I also need to get rid of the substrate that I have in there too, which I thought was odd but I am up for it.  Any advice is welcome.  I am doing FWLR tank so no reefs or anything too complicated right now. 

Saltwater tank you must need an rodi unit first off, second its best to get sand specifically marine sand as it helps to speed up the cycle and helps to buffer the water. Live rock also helps to cycle tanks quicker. 

[gardenman]

Marine substrates help to buffer the water to keep the pH stable. Live rock will often help achieve that also if there's enough used. A fish with live rock tank isn't drastically different from a pure freshwater tank. You have to top off evaporation with freshwater as the salt stays behind. Water changes are obviously done with premixed saltwater. Keep an eye on the salinity and try to keep that as stable as possible. It's pretty much the same thing with just a few more variables tossed in.