300 gallon reef to freshwater questions

[Lacey Grant]

I have a 300+ gallon reef tank. Let me tell ya… It has been fun, frustrating and extremely expensive!!! I don’t even want to know how much money I have invested in this tank and lost. Not to forget about the amount of maintenance.
It was a freshwater tank before stocked with Oscars, Catfish and arrowana etc. 

I am thinking about making it into a freshwater planted tank with community fish. 

has anyone done anything like this? If so what did you do to convert to  Freshwater? 

[AllFishNoBrakes]

That’s a rad tank!

I’ve never done it, but I would image returning it back to freshwater would be pretty simple. Basically the opposite of turning it into a reef tank. 
 

Personally, I would pull all the live rock (unless you’re wanting to use that in the freshwater set up), drain the tank, swap substrate if you plan to do that, and clean out the sump. From there I would add whatever hardscape and/or plants to start, fill it up with freshwater and dechlorinate as necessary, and cycle the tank. I believe that the freshwater and saltwater nitrifying bacteria are different, so you’re going to want to cycle the tank again. 
 

You would probably also want new, or to go back to freshwater lighting. 
 

Just my $0.02 and how I would do it. 

[face]

I bought a used 110 that was at one point a reef tank very basic compared to yours but ya it’s pretty simple what is lighting yours ? Protein skimmer  can be removed probably doesn’t need the dosing pumps but they may be useful in a higher tech tank how planted do you want it co2 injected or just low tech  and dependent on fish and your location the chiller might be not necessary 

[Biotope Biologist]

Biggest thing is remove all salt in the tank. Any residue can be lethal to fish and plants. You could go brackish and have the best of both worlds it is starting to gain traction and popularity as more of those fish species become captive bred.

 

Sump and filtration can be kept the same depending on if you have a fixed rate pump or one that you can dial down. Just use spray bar if it’s too much flow. Don’t want to uproot the plants!

 

I would not keep the lighting. The blue shifted reef lights make everything in a freshwater tank look… like a pet store display. Luckily reef lights have pretty good used resell value. You will want red as your secondary light to the white led. Kessil would be my go but finnex stingray and ACO lights are also great

 

As for inhabitants I like a big docile cichlid like discus or geophagus with larger schoolers like dennison barbs and danio

 

If you go brackish mollies are fun or a freshwater demoiselle pair with some gobes and scat or there are quite a few brackish puffers that aren’t absolute terrors like their saltwater counterparts. These stay smaller and can be kept in small groups 

[Tlindsey]

I personally converted a couple of aquariums from saltwater to freshwater. Agree with everyone not difficult. Depending on what biomedia you used it can be used for freshwater. For example I use my bio balls that were once used for saltwater. As @Biotope Biologist stated rinse biomedia very well.  

[Woowala]

I did this with my first reef, a 75 gallon, way back in high school.  Changed it over to a big colony of Julidochromis transcriptus.  Ditched the skimmer and all the hardscape, kept the wet/dry and some of the lights.  Relatively painless.

The thought of maintaining and paying for a 300 gallon reef gives me anxiety lol. 

I would do a tanganyika tank- julies or some kind of rock dweller, cyprichromis for the top,  an area for shellies maybe,  and some open sand bed for enantiopus or some featherfins. So many options with 300 gallons. 

[Lennie]

Just an opinion, when you have all this system set up, how about just rehoming the fish that would potentially eat the macroalgae, and turn it into a macroalgae tank instead?

They basically look like a planted freshwater tank but considerably better, as you can reach those bright colors without investing on  co2 setup and you wont need to deal with all those salt, tank resetting, cycling from zero, buying soo many things new and so on

 

Also if Im not mistaken, macroalgae helps with water parameters too, which I believe would lessen your workload like plants in freshwater?

Look at these examples, beautiful! And you have already almost everything set up for it