Reusing an old tank

[Dyln]

Hi everyone, I could use some advice. I left my tank completely unmaintained since March 2024 (there were no fish or coral in it). I turned off all the equipment, and over time, the water evaporated significantly. Now, both wavemakers are sitting above the waterline, and the internal filter and skimmer are only partially submerged. The heater and backup heater, however, are still fully submerged.

I'm considering restarting this tank, but I’m not sure how to proceed. I assume the beneficial bacteria are gone, so I’ll need to cycle the tank from scratch (have live rock). Can I simply refill the tank with fresh water (salinity should go back to desired range), or do I need to take additional steps? Should I be concerned about potential damage to the silicone seals or any of the equipment due to the prolonged period of inactivity?

Any advice or recommendations would be greatly appreciated. Thanks in advance!

 

[PharmrJohn]

That water needs to go. It's also likely that there's been death in the tank (microbial at the very least). I'd clean the tank and really start from scratch. That'll give you a chance to check the seams and just make sure all is well.

 

[Dyln]

That water needs to go. It's also likely that there's been death in the tank (microbial at the very least). I'd clean the tank and really start from scratch. That'll give you a chance to check the seams and just make sure all is well.

Thank you for your input! I was planning to do multiple water changes and thoroughly clean the tank, including the rocks, sand, and filters without removing everything from the tank. The tank is less than two years old, so I’m wondering what specific signs I should look for to assess the silicone's integrity. Also, do you think it's advisable to reuse the existing equipment, or would it be better to replace them altogether?

 

[XtraKargo]

Check to make sure the silicon that wasn't submerged isn't stiff or rigid. As long as it is still supple then you should be fine. Gear, just make sure there's no rust, no cracked power cords or the like, then give it a vinegar dip for a while, or in citric acid and scrub it up. If it runs, I'd say your good.

 

[Dyln]

Check to make sure the silicon that wasn't submerged isn't stiff or rigid. As long as it is still supple then you should be fine. Gear, just make sure there's no rust, no cracked power cords or the like, then give it a vinegar dip for a while, or in citric acid and scrub it up. If it runs, I'd say your good.

Really helpful. Thank you so much.

 

[exnisstech]

If the tank is only two years old it should be fine as far as the silicon. I have not noticed the silicone out of water drying out and deteriorating. If that was the case all of the silicone above the water line would be failing on every tank. I also have tanks that are years old and sit dry for months to years and I set them up as QT and emergency tanks. That statement that silicone needs to be submerged or it dries out just doesn't make sense to me. Silicone is used for so many things and many of them have nothing to do with water.

 

[Asm481]

I would think several large water changes while blasting the live rock to shake out any detritus would get the water in shape saving any microbes that would certainly be there. As far as the pumps, a good soak and clean in citric acid you should be good. Don't use any bleach or other cleaners to minimize the new cycle which should be real short.

 

[Eric R.]

Yes, as long as there are no large visible bubbles in the seams, they should be fine. But it being left partially dry shouldn’t affect this.

I’d clean and inspect the equipment, especially checking for rust or exposed seams on any magnets. If the equipment runs, I’d still use it, unless your budget exceeds your risk tolerance. Always good to have backup equipment on hand and a plan for if any piece of equipment fails. Skimmers aren’t as big of a deal failing as a return pump if you don’t have a replacement on hand for instance. But doesn’t hurt to have a replacement skimmer pump on hand if you can.

My personal approach would be to not remove old sand from the tank. I would partially fill it up with DI as you suggested, then give it all a good stir and vacuum to get the gunk out, then do a large water changes until the ammonia and nitrate levels are stable and in a good range. Repeating the stirring and gravel vac process a few times until things look noticeably cleaner probably wouldn’t hurt. I would give the rock a scrub with just an old toothbrush in some saltwater to get rid of any dead stuff on the surface and give it a good swish then throw it back in. Then I’d just let the tank sit with a heater and keep salinity stable with some new established live rock added for some weeks (as long as you’re patient for) until you see signs of growth and life on the old existing rock. Minimal light. Basically cycling a tank again.

I prefer that than starting from sterilized scratch, as I think the succession of bacteria and other benthic microorganisms (aka benthic succession) will go faster than if you sterilize and start over. People used to start with “live” rock back in the day that had all sorts of die off from shipping that they had to cure, but I feel that that was a faster and more successful approach than we often see today with people starting with sterilized rock, sand, and no nutrients and then battling dinos and hair algae for months until they get stability.

 

[Dyln]

If the tank is only two years old it should be fine as far as the silicon. I have not noticed the silicone out of water drying out and deteriorating. If that was the case all of the silicone above the water line would be failing on every tank. I also have tanks that are years old and sit dry for months to years and I set them up as QT and emergency tanks. That statement that silicone needs to be submerged or it dries out just doesn't make sense to me. Silicone is used for so many things and many of them have nothing to do with water.

You got a point there. I was concerned because the LFS gave me some mix advice.

 

[Dyln]

I would think several large water changes while blasting the live rock to shake out any detritus would get the water in shape saving any microbes that would certainly be there. As far as the pumps, a good soak and clean in citric acid you should be good. Don't use any bleach or other cleaners to minimize the new cycle which should be real short.

Thank you. I assume white vinegar is fine to clean the pumps as well?

 

[BristleWormHater]

I would cure the rock. Stagnant water is the PERFECT breeding ground for all kinds of harmful bacteria and amoeba. Clean EVERYTHING, then you should be good to go :)

 

[BristleWormHater]

I would think several large water changes while blasting the live rock to shake out any detritus would get the water in shape saving any microbes that would certainly be there. As far as the pumps, a good soak and clean in citric acid you should be good. Don't use any bleach or other cleaners to minimize the new cycle which should be real short.

Curing the rock would be a much better option. In room-temp stagnant water all beneficial bacteria has likely died off and been replaced with harmful bacteria and amoeba.

 

[Dyln]

Yes, as long as there are no large visible bubbles in the seams, they should be fine. But it being left partially dry shouldn’t affect this.

I’d clean and inspect the equipment, especially checking for rust or exposed seams on any magnets. If the equipment runs, I’d still use it, unless your budget exceeds your risk tolerance. Always good to have backup equipment on hand and a plan for if any piece of equipment fails. Skimmers aren’t as big of a deal failing as a return pump if you don’t have a replacement on hand for instance. But doesn’t hurt to have a replacement skimmer pump on hand if you can.

My personal approach would be to not remove old sand from the tank. I would partially fill it up with DI as you suggested, then give it all a good stir and vacuum to get the gunk out, then do a large water changes until the ammonia and nitrate levels are stable and in a good range. Repeating the stirring and gravel vac process a few times until things look noticeably cleaner probably wouldn’t hurt. I would give the rock a scrub with just an old toothbrush in some saltwater to get rid of any dead stuff on the surface and give it a good swish then throw it back in. Then I’d just let the tank sit with a heater and keep salinity stable with some new established live rock added for some weeks (as long as you’re patient for) until you see signs of growth and life on the old existing rock. Minimal light. Basically cycling a tank again.

I prefer that than starting from sterilized scratch, as I think the succession of bacteria and other benthic microorganisms (aka benthic succession) will go faster than if you sterilize and start over. People used to start with “live” rock back in the day that had all sorts of die off from shipping that they had to cure, but I feel that that was a faster and more successful approach than we often see today with people starting with sterilized rock, sand, and no nutrients and then battling dinos and hair algae for months until they get stability.

Thank you for taking the time respond in detail. I agree, prefer not to sterilise the tank if possible. In terms of equipment, I don't want to throw away equipment if I can use them. But I am cautious not to harm fish or cause a potential fire! I always keep emergency kit just in case.

 

[Dyln]

Curing the rock would be a much better option. In room-temp stagnant water all beneficial bacteria has likely died off and been replaced with harmful bacteria and amoeba.

Wow. This is new info. I don't wanna play with amoeba for sure. How does it survive without any food?

 

[BristleWormHater]

Thank you for taking the time respond in detail. I agree, prefer not to sterilise the tank if possible. In terms of equipment, I don't want to throw away equipment if I can use them. But I am cautious not to harm fish or cause a potential fire! I always keep emergency kit just in case.

You had all the equipment OFF, right? I would completely sterilize then, water circulation is extremely important, all kinds of bacteria that you absolutely do not want will build up in stagnant water, hence why people use a powerhead and heater to culture live rock.

Wow. This is new info. I don't wanna play with amoeba for sure. How does it survive without any food?

Stagnant water is it's own ecosystem. I'm not saying there is amoeba, but it is a great environment for them, they would be eating bacteria and other microbes.

 

[Dyln]

You had all the equipment OFF, right? I would completely sterilize then, water circulation is extremely important, all kinds of bacteria that you absolutely do not want will build up in stagnant water, hence why people use a powerhead and heater to culture live rock.

Stagnant water is it's own ecosystem. I'm not saying there is amoeba, but it is a great environment for them, they would be eating bacteria and other microbes.

Make sense but I just read that they can't survive without oxygen. No water movement no oxygen, right?

 

[Eric R.]

You had all the equipment OFF, right? I would completely sterilize then, water circulation is extremely important, all kinds of bacteria that you absolutely do not want will build up in stagnant water, hence why people use a powerhead and heater to culture live rock.

Stagnant water is it's own ecosystem. I'm not saying there is amoeba, but it is a great environment for them, they would be eating bacteria and other microbes.

Curious where you learned this information about amoebas and harmful bacteria. Do you have a background in microbiology? I don't want to assume that since you've only been reefing since July that you don't know what you're talking about, but I don't know that your point is common knowledge so I'd like to know more. What strains of bacteria would you be concerned about in this case?

I would imagine the microbiome has shifted due to the increased salinity and decreased circulation. But I would think that by adding heat, circulation, regular water changes, and gravel siphoning would promote the sort of conditions that would cause the microbiome to shift back to a favorable makeup. I wouldn't throw anything other than some more live rock in for at least several weeks. I wouldn't suggest doing a water change and adding $1,000 in coral and fish right off the bat.

 

[exnisstech]

You got a point there. I was concerned because the LFS gave me some mix advice.

When in doubt always ask. Sadly there will almost always be mixed advice, even more so now in the age of instant information :crying-face:

 

[Idech]

Thank you. I assume white vinegar is fine to clean the pumps as well?

There have been reports that vinegar will damage equipment. The safest route is citric acid.

 

[Fish Fan]

Make sense but I just read that they can't survive without oxygen. No water movement no oxygen, right?

No water movement means greatly reduced oxygen, but you're system didn't go to a zero oxygen state. Some oxygen will still diffuse into the water even if the surface isn't moving, maybe not enough to keep fish, which is how I think we typically think of it. But microbes are not fish, and are remarkably resistant and capable, and can thrive where nothing else can.

And even if your tank did go to zero oxygen, there's an untold number of anaerobic microorganisms that thrive thrive in low to zero oxygen environments.

Stagnant water is it's own ecosystem. I'm not saying there is amoeba, but it is a great environment for them, they would be eating bacteria and other microbes.

The protozoan commonly known as an amoeba is a freshwater organism, and will not be found in saltwater, especially not hypersalinated saltwater, though I agree with your overall point; nasty, old saltwater = yuck city lol!

I'm on the side of completely restarting this tank, and I rarely say that, but given the time it's gone stagnate....

I'd break it all down, scrub and clean all the gear with citric acid. Inspect the tank seams, but I don't think you'll have a problem there. I have left tanks FOR YEARS in between use and have never had a problem.

For the rock and any sand you may have, I *think* somewhere you said you have some live rock to restart this tank?? If so, I'd suggest just tossing your existing rocks and sand, and restarting this tank using a quality live rock and/or sand. The benefits of going live rock vs. dead rock are many.

If you really want to reuse your rocks and sand, look into "bleach curing". This method quickly cleans yours rocks of all organics, and makes them bright white and new again.

I hope that helps, and best of luck!