Converting Saltwater tank to Freshwater

  • #1

I just purchased a 60 gallon hex tank that was set up as saltwater. How much does this tank need to be cleaned. It seems like there is residual salt in many places. I'm trying to get it all off but if I don't get every bit will it be bad for fresh water fish???

Do you have any other recommendations to prepare this for freshwater again?

  • #2
I believe clean as well as you can with fresh water (plenty of elbow grease). Fill, condition water, maybe another water change, and then start cycling.
  • Thread Starter
  • #3
Old Sloppy
  • #4
Don't worry too much about the salt residue.
60 gallons of clean water will make the salt disssapear.
You will be unable to even detect it's presence.

Harry S.
Semantic Drift
  • #5
Anyway, a little salt never hurt a freshwater tank - a lot of people add salt to their freshwater setups (I realize freshwater aquarium salt and sea salt are different, but I don't think any harm could come from a little reef salt).
  • #6
If you want to clean up the salt deposits try some arming hammer baking soda. I used it on some calcium deposits and such that you get on the filters and it just came right off...

  • #7
are you sure baking soda? or was the baking soda just used as an abrasive?

i've used diluted vinegar with excellent results.
  • #8
I am picking up my free 50 gallon tank(used for saltwater) in a couple of hours and have decided that I just don't have the time or the experience yet to maintain a saltwater aquarium set up just yet. SOOOO I need to clean the tank out. I was wondering what would be the best method to clean it out with. I've been reading about a bleach/water solution and a vinegar/water solution. Would one work better than the other? Also - would I be able to keep any of the material it is coming with - filters, fake plants, rocks, etc... It is a sand bottom so I won't be keeping that. Just wondering... Thanks for any help!
  • #9

I use a 19 part water 1 part bleach mixture on all my tanks (even the ones I buy brand new). generally what I do depending on the size of the tank is fill it up completely (with the bleach/water mixture) either in the bathtub/shower or outside and I fill it very slowly so I can check for leaks. I let that sit for 24 hours (again to check for leaks), then dump out the water, and fill the tank back up with JUST water (no bleach) and rinse it very, very well. then I put the tank wherever it's going to be permanently, fill it very slowly again with lots of dechlorinator (to get rid of any bleach that may have been leftover).

you can definitely keep the other stuff that comes with it, i'd just either bleach or boil it, whichever is possible. for the filter, I would run it on the tank (without any filter media inside it) when you're bleaching the tank, and run it again when you're rinsing, and again when you fill with dechlorinator.
  • #10

Thanks for the tip. I gave it a go but I think it is a lost cause... The guy who gave us the tank had told us that it "had a bit of algae". When we arrived at his house we couldn't see through the glass it was so caked with black, purple, and green algae. We still took it though. The filters, powerheads, and protein skimmer were so clogged with algae that they weren't salvageable. The hoods and lighting set up was so caked with salt and it was all in the electrical parts that I didn't feel safe plugging it in. I put the bleach in the tank and started scrubbing away the algae. After the algae was gone we noticed that the glass was covered with foggy residue and there were tons of tiny scratches all over the glass.

After that we looked at getting the parts for everything we needed to replace and it came out to $175ish....we could get a 55 gallon tank set up with everything for $201 brand new at wal-mart.

So yeah....I don't think it is worth saving at this point. I guess that's what you get when you get something for free....

I attached a picture so you can see what I am talking about. I have never seen anything so filthy in my life. The guy said there were like 3 or 4 fish. We only found 1 and "part" of another that was floating on top...Just incredible...
  • #11
wow....yeah that's pretty MIGHT be able to be salvaged but it's going to be a lot of work for you
  • #12
HI all.

Its an odd question I know. I have my reasons though.

In short,
I tore it down, removed all the coralline algae and tube worms etc I could from glass and filters, but its impossible to get it all. Its been running for 5 years or so. How bad do you think what is left will leech into the water? Would I be better off using new filters? Could I offset what does with another medium until the calcium eventually fades through water changes or will it take years?

I'm using RO water which I think will help...but what else?

I've only found one other post like this. Anyone else tried it?

Thanks for any responses.
  • #13
I changed out both my tanks from Saltwater reef and FOWLR to freshwater tanks. I did what you did - and I also let the mechanical media sit for a while in a vinegar solution.. I rinsed out the bio media from my filters and let sit for about a day in a vinegar and water solution and all of the other media. I then started the Freshwater fishless cycle - with some media from another tank (nowdays you can use TSS to get started quicker - if you don't have media from another Freshwater tank to begin bacterial colonization. MY GH, and KH weren't any different from my tap water. However, be aware, that with fresh water tank, using RO water, you are going to have to add trace elements and buffering. So for me - I did not notice any residual effects upon my water chemistry.
  • #14
Excellent, thank you!
That was exactly what I was looking for.
  • #15

not sure where to put this post exactly, so I thought I would start here. I currently have a 60gal cube (24x24x24) Saltwater tank setup that I want to convert to FW. I have done some reading and research regarding cleaning, so I think I have that under control. My questions are:

1. Can I still run the sump tank that I have now (after it is cleaned of course)?
2. I have a RO/DI unit as an auto-topoff...can I or should I continue to use that with a Freshwater setup?
3. Do I need/is it necessary to continue to run a protein skimmer?
4. What would I need to look at as far as filtration?
5. And finally (for now) lighting. I have a MarineLand LED light. Will this be ok for Freshwater or will I need something else.

Thanks for any help/advice you can give me.
  • #16
1. Yes, Freshwater sumps are great!

2. Yes, you might as well continue using it

3. No, not really. I don't run any on my Freshwater tanks

4. I recommend eheim canisters, or sun sun canisters ( and )

5. Ought to work, but specification of the model would be helpful

Welcome to fishlore, good luck, and keep us updated!
  • #17
Thanks for the quick reply. The light I currently have is this one

The other question regarding the filtration is, I would assume that I can set it up next to the sump and have it take from the "in" side of the sump and discharge into the area where the pump back to the tank is instead of directly into the display tank...right? (I hope that made sense)
  • #18
You have an incredible light-No worries for sure. And for the filter, yes
  • #19
Awesome. So if I want to have live plants (eventually), do I need to have a certain type of substrate?
Are there any tricks to cycling the tank? I know with Saltwater there are a few different ways to cycle faster, but not sure about FW.
  • #20
Lot's of great questions so far You CAN buy planted tank substrate, you can buy gravel, or you could use dirt... I use . I use TSS in all of my tanks and cycle with either a feeder goldfish or danios.
  • #21
Is this what you are referring to with TSS? Total Suspended Solids (TSS)
Also, if I have plants, is there a need for additives similar to Seachem Flourish Excel?

Add on question for the substrate. I was looking at the same stuff you are deep do I need to go ( many bags would I need to purchase) for a 60gal (24x24x24)?
  • #22
I'd get 80lbs, I use ~55lbs in my 40... And TSS is tetra safe start
  • #23
Ok in the sump, what do you put in there? Moss? Sand? Gravel? I am used to a Saltwater setup but still learning about FW.
  • #24
Ok in the sump, what do you put in there? Moss? Sand? Gravel? I am used to a Saltwater setup but still learning about FW.
I used to put filter shrimp (Bamboo, I think) as well as moss, snails, and about 1/4 inch of substrate.
  • #25
Okay I wasn't sure where to post this so I just picked the Saltwater begginers, even though I'm not quite a begginer anymore.
so I plan on moving in the next year or so back to Arizona (I currently live in Illinois) and I plan on selling my saltwater fish because I don't think they would make the trip and I would t be able to get my tank setup right away anyways.. So I plan on selling my fish and crabs and complex cleaning out my tank so when I get to AZ in about a month in a. Start all over this time with freshwater.
My question is how do you go about cleaning the tank and the tank media filters ect.

And for fish I'm considering buying a German blue ram as well as other peaceful community fish for my 30 gallon. Any suggestions
  • #26
In that situation, I'd just go with new filters, instead of trying to clean out the old ones. While it's possible to clean then, you want to get no salt into the new water. But my guess would be vinegar and water for cleaning the tank and any equipment.

30 gallon tanks have a decent stocking selection available. The german blue rams I would wait until the tank is well established since they are pretty delicate fish for freshwater. I'd add something else such as schooling fish and let the tank establish for 2-3 months before adding the german blue ram.
  • #27
I was considering either a school of red minor tetras or tiger barbs debating on which. As far as the filter I would like to save it if I can (it's a really nice filter) marineland penguin 350.

And I do also plan to have it heavily planted (this will be my first time having real plants)
  • #28
I took down a 65G Drilled tank used with salt water for a few months, and want to convert it over to a cichlid tank. Below is a 25G sump , with 2 socks, skimmer chamber, refigum chamber, and return chamber.

I understand I don't need to use a skimmer any longer.

What would I use in the skimmer area for filtration ?

Do I still need to use a ATO like salt water?


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  • #29
Any help is appreciated
  • #30
I an going to tag NavyChief20 he is very good with stuff like this!!
  • #31
Ok great, thanks!
  • #32
Hey just saw this. Been a long weekend and I'm exhausted. Step one is flush and clean the whole thing. You're right you don't need the skimmer so that could be converted to some media area. Ill get back to you tomorrow I need to be up in 5 hours.
  • #33
ok thanks, I'm just trying to figure out how to use the sump,. and what media goes where

Thank you
  • #34
How is the fuge and the skimmer chambers connected? It a little hard to tell in pics.

If it was me, I would have the skimmer chamber filled with media. Some options include K1 (may need something like an airstone to ensure movement, but it does 'self clean'); lava rock, bio balls or filled with sponges (cut to size to fit the chamber from front to back, so it forces the water to flow from left to right)... or a mixture to suit.

As for the fuge, I would use to to grow fast growing and hardy plants (or have pothos rooting in the water) for ammonia and nitrate removal. Some cichlids also require high amounts of vegetation in their diet, so growing plants like duckweed or elodea would provide a tasty snack!

In saying that, if that's not to taste, you can also fill it up with more media (and just have pothos rooted in it!)
  • #35

Here's a link with better pics of the sump:

The skimmer chamber has flow through it, then into the refugium, then into the return pump area.

This is what I was thinking, I just did alittle reading on dumps for freshwater.

Socks for mechanical,
Skimmer chamber filled with a bunch of sponges or something for biological.
I was thinking of a laundry bag keeping everything in, so when I clean that area, I could just rinse them in tank water.

The refugium area more bio like cermic rings, etc

I wasn't considering bio balls because it's not a wet/dry ?
  • #36
Looking from the front you have the down tubes that then go into filter socks. Keep that. Use filter socks or some coarse sponge. The next bay you can dump tons of lava rock in, or mesh bag it and you could put plants in there as well. Final bay that taps into the return pump you could use for more media or plant that area. Either way it is extremely modular and you have tons of options. The sponge or sock will work excellent as a water polisher/mechanical filter.
  • #37
Lava rock like in gardens you buy a bag at lowes or home depot?

So 2 socks for mechanical, lava rock in middle , course sponges in 3rd refugium area , then return section.

If I want to add plants , would I need to add mud or something for them to root in, or just pile the lava rocks around them?
  • #38
Lava rock like in gardens you buy a bag at lowes or home depot?

So 2 socks for mechanical, lava rock in middle , course sponges in 3rd refugium area , then return section.

If I want to add plants , would I need to add mud or something for them to root in, or just pile the lava rocks around them?
Yup just plain old lava rock. Cheaper than ceramic and more surface area.
  • #39
Wow! I was going to spend a ton for cermic rings to fill that size of a section

Plants need mud or just put them in the lava rock?
  • #40
Wow! I was going to spend a ton for cermic rings to fill that size of a section

Plants need mud or just put them in the lava rock?
My plants are all in tank but I use sand. I'm not great at planted tanks. My plants in sump I have just floating.

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