# How to clean residue/mold



## BBXB (Oct 7, 2012)

Hi, got a used tank but the rim has some mildew/mold that wont come off just using towel and water. Is there any tricks that I can use to clean it that is shrimp safe? I have heard of using magic eraser, anyone tried this before? Thanks.


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## Kimchi24 (Mar 22, 2013)

i think vinegar should work. just get a spray bottle, fill half of it with vinegar and half with water. spray that sucker and let it soak for like 5 mins. wipe it off and repeat haha. bleach may work too but you have to use a lot of dechlor after to get it safe for shrimps


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## Fishfur (Mar 4, 2012)

Just in case, are there shrimp in this tank already ? If so, you'd have to be very careful not to let anything you use or scrape off fall in the water.

But I'm hoping it's empty. Then you can try several things and so long as you make sure to thoroughly rinse out the tank afterward, any shrimp that come to live in it will be just fine.

Does it have a plastic rim ? If so, most stains will come off that plastic pretty easily. A heavy duty scouring pad, even a steel wool pad, would do the trick, as would a razor or paint scraper. If you use any scouring pad, vacuum the tank before you rinse, that will remove any tiny particles of broken scouring medium. Steel wool will rust if any gets left to get wet. But don't use the kind with soap already in it.. that soap is quite hard to get off. Plain steel wool, or balls of stainless steel or brass scours all work.

Magic Erasers are great for some things, but they don't last long. They become squashed & crumble quite fast. If you have one, try it and see if it works. A wipe with damp towel afterward is all you need.

If you are sure it's mould or mildew, a mixture of a couple of tablespoons of baking soda with a litre of warm water should help remove it. Rinse well, baking soda is used sometimes to raise pH, so you won't want it in there.

However, I think you are much more likely to have hard water stains, rather than mildew. Mould and mildew are not commonly found on glass aquariums unless they've been used as terrariums, but hard water stains are very common indeed.

For hard water stains, hot vinegar and a razor or scraper should get most of it off. A razor scraper often works even without the vinegar. I prefer to use CLR instead of vinegar, it's much more effective, but it also costs quite a bit more. CLR is non toxic, so all you have to do is rinse with water. I've never had any issues with any animal in a tank I cleaned with CLR, and that's every glass tank I have.

Sometimes that whitish looking band around the top edge of a tank turns out to be etched into the glass. If nothing you use is taking it off, chances are it's etched. The only way to make that go away is to polish the glass like a gemstone, using several grades of fine polishing compound. It's very time consuming even using a power tool, and not worth it.

But most of the time, etching sort of disappears once it is wet. So it won't be visible once the tank is full, unless you don't want the water as high as the marks are. I think almost all my tanks have at least some bit of etching around the top, because they were all well used when I got them.

If a tank has no hard water stains and you are good about regularly cleaning the inside of the glass at the water line, you can likely prevent etching from happening, but leaving hard water stains to build up for long periods of time seems to be at least one cause of etching.

You see similar etching on some glassware that has been through many, many cycles in a dishwasher, especially with those new tablet style dishwasher detergents. They are pretty caustic and are not safe for several surfaces that are otherwise ok in a dishwasher. But even regular dishwasher detergent will etch some kinds of glassware over time because it's all caustic to some degree. [ caustic; meaning very alkaline in pH]

Once a tank has become etched, you are pretty much stuck with it.


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## BBXB (Oct 7, 2012)

Thanks for the prompt and detailed responses. The residue is only on the plastic rim parts, so would vinegar or CLR be better? They are both shrimp safe correct?


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## BBXB (Oct 7, 2012)

Also, not 100% it is mildew. Can just be buildup of some sort, wish I can provide better details. Essentially the rim is supposed to be white(cream) but is now a dark yellow.


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## pyrrolin (Jan 11, 2012)

Its good to fill a used tank with water and put a couple cups of bleach in and let it soak for a bit to kill anything, rinse well and use double dechlorinator when setting up to be extra safe


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## Fishfur (Mar 4, 2012)

Ah, I have a pair of used tanks with that light coloured trim on them. It was badly discoloured when I got them, stains, browning and generally filthy looking. They were fish room tanks, 20 years old but in very good shape aside from the stained trim.

I think I used a stainless steel scrubbie to scrub that icky plastic and they turned out great. I finished off with a synthetic scrub pad, one of the heavy duty ones that is NOT safe for non stick cookware. Between the two pads, that plastic ended up looking almost new. The colour lightened a lot and was nice and even, without any stains left anywhere, and that's all I did. Scrubbing removed every trace of dirt, marks, off colour and stains. In some places, those rims were practically tea coloured, I think just from age, maybe from exposure. I never thought they'd come up as nicely as they did.

For hard water buildup, I prefer CLR myself because it works faster. But hot vinegar will also take off any buildup from hard water. If it's dirt or something else that's been allowed to sit there, scrubbing or a scraper should remove it without too much effort. If there are actually shrimp in the tank when you do the cleaning though, I would not use any liquid.. just scrub. CLR is non toxic and so is vinegar but if there are shrimp living in the tank, and they somehow happened to get a dribble of vinegar or CLR on their shells it could harm them.. their shells have a lot of calcium content, which will dissolve in strong acid.

If the tank is empty, both CLR and vinegar will rinse clean with just plain water and leave no residue that can harm anything. If the tank is empty, giving it a good rinse or soak with some bleach, like Pyrrolin said, is a good idea too. Disinfects, kills any algae that might be lurking. Rinsing will get rid of it, but if you have any concern, adding a bit of extra dechlorinator to the last rinse will neutralize any chlorine that's left.

If there is built up stuff on the plastic, typically it's mostly minerals, often from an air stone or filter. It can also be crud and dirt that's been allowed to accumulate. I think you'll be surprised at the results you will get from a good brisk scrub with a good heavy duty scrub pad of some kind. Even plain steel wool will work, if you have that on hand.


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## pyrrolin (Jan 11, 2012)

on glass, a razor blade helps greatly to, but doenst work so well on plastic, cuts it.


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## Fishfur (Mar 4, 2012)

Depends on your technique . If you drag it backwards, rather than pushing it ahead like a snowplow, it will just scrape..but I admit, it takes a bit of practice to get the method down. I actually prefer a dulled blade if I need to use one for this kind of thing, as it will be less likely to scratch if I don't keep it dead flat to the surface. But it can be hard to get a scrubbie of any kind into a tight corner, so the blade is often the only way I can get the bits out of the corners.


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## BBXB (Oct 7, 2012)

Again, thanks for all the info. So bleach is shrimp and fish safe? I would've never guessed. Also,prime would be considered a dechlorinator correct?


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## Zebrapl3co (Mar 29, 2006)

Bleach is not shrimp or fish safe.
The idea is to use bleach to get rid of your mold problem, then wash like hell to get rid of all the bleach to make is safe again. One good thing about using bleach is that it's an unstable compound. That means given time, it will dissipate into the air. Hence, if you do a bad job at cleaning it. Leaving it around for 1 week will by default dissipate it. Hence ensuring a safe tank for your fish and shrimp.

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## pyrrolin (Jan 11, 2012)

don't put bleach in a tank with shrimp in it, not that safe. But as the other person said, bleach is unstable and will be gone no matter what after some time. 

Prime is a dechlorinator. Bleach and chlorine are basically the same thing if not exactly the same thing.

I just rinse the tank well and when I fill for use, I use double dechlorinator. Bleach also becomes inert when it tries, turns into a salt. So can technically dry the tank, let it sit for a day and then it is safe. Bleach/chlorine burn off fast, reason you keep having to add chlorine to pools, especially with sunlight.


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## cape (Jun 18, 2010)

For all the people that suggests bleach to disinfect tank, if the tank is used but has been out of order and dried. Is disease and algae really a concern?


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## pyrrolin (Jan 11, 2012)

better safe than sorry


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## Fishfur (Mar 4, 2012)

If the tank glass is clean and there is no debris in the tank, you don't have to bleach it. Simply cleaning the glass and rinsing thoroughly should do the trick.

A lot of us use bleach simply because there is no way to know, usually, with a used tank, whether or not there was any disease in it. Some disease organisms can be very persistent and may regenerate when water is added. Bleach kills most bacteria and moulds, so it's a safety measure more than anything. Peace of mind.

Bleach is a mixture of water and sodium hypochlorite. Same stuff they use for swimming pools. Standard strength bleach is about 5.25%, and some of the 'extra strength' ones are 6%. Some of the cheap brands are as low as 3%.. so you don't really save money, you're just paying fore more water in the bottle. Bleach used to come as a powder that you dissolved at home until somebody thought of selling it predissolved, and lo and behold, Chlorox was born. 

As all have said, it's very volatile and quickly gasses off into the air when exposed to air, especially if sunlight is also present. Even if you don't rinse at all, if you allow the tank to dry out completely, the chlorine part of the bleach will be gone. All that's left is salt, the sodium part of the combo, which you can wipe or rinse away. That's how salt pools work.. the chlorine is split off into the pool filter where it acts to disinfect the water while the salt part goes into the pool, so there's no smell of chlorine and no irritation to skin or eyes as there is when the chlorine portion of the bleach goes into the pool itself. Don't ask me how that's done.. I have no idea.

So if you want to use bleach, don't worry about it damaging the shrimp later on. So long as you rinse well or allow the tank to dry completely, and use a bit of extra dechlorinator if you chose to rinse, you are good and the shrimp will be fine. I've rinsed every tank I own in bleach and they all have shrimp in them. One has frogs in it and they are even more sensitive to many chemicals than shrimp are.


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