converting brackish to salt

Keith Hotchkiss

I have a 30 gallon brackish tank with 2 figure eight puffers, 1 green spotted puffer and 1 mono. I was wondering if I could keep these fish but go saltwater now. I was hoping to do something with so live rocks but I can't figure out if it will work. If there's any ideas I would love to hear them. Thanks

Pasfur

If your only intention is to keep live rock, then yes, you can raise your salinity to the proper level and then add live rock.

Unfortunately your efforts will be wasted, because the puffer fish will pick almost all external life from the live rock. Additionally, your aquarium would not have the stability of a marine aquarium without being set up properly to begin with, which would result in less life surviving inside the rock long term.

If you are actually interested in a marine aquarium, then you would be well advised to start over from the beginning.

wake49

Keith: What equipment do you have now?
Pasfur: What equipment is different in a salt than a brackish?

I am trying to figure out if I want to make my twenty a puffer only tank, or a dwarf lion tank. I want to know how to properly set up this tank so I could make such a switch from brackish to marine with no problem.

Pasfur

There is really no comparison of equipment between freshwater and marine. Everything is different. If you have a hang-on filter on a freshwater tank, then you MIGHT use it on your saltwater tank for water movement, but you won't use the filters pads, sponges, biomedia, or bioballs. At best, you will use a hang on for activated carbon, but that is all.

There is really no such thing as converting from brackish to marine without breaking down the tank, but you will be able to use some o the same equipment. You can buy a fully submersible saltwater heater and use it on both systems. You can use aragonite sand in a brackish setup, which you can move into a marine aquarium if you clean it well inbetween. You can also use power heads for water flow in a brackish tank, and they can easily move to a marine system.

The problem with converting is huge. A properly setup marine aquarium uses a Protein Skimmer, Live Rock, and aragonite sand. No other filtration is used. In fact, additional filtration will usually only HURT water quality in a marine aquarium, with the exception of activated carbon.

This type of marine system will not work to fully filter a brackish aquarium, because the live rock will not survive at this lower salinity, the protein skimmer will not function as efficiently, and the aragonite sand will never become live without the life on the live rock to seed it. You could just keep the salinity at a marine level, but the brachish fish will eat most of the life from the live rock, which would be a great waste of money.

You could add a biological filter, which is normally used on a freshwater tank, but this would pump Nitrates into the aquarium which would require nearly a 100% water change prior to the conversion to marine. If you are going to do a 100% water change, then you are basically starting over.

So... my advice is this. Set up a brackish tank, using basic freshwater equipment. This is the inexpensive way. Then buy another tank and do a marine aquarium the proper way, starting out right from the beginning.