# Removing Hard Calcium Stains



## KnownSyntax (Mar 15, 2014)

I recently got my hands on a used tank from a friend, however it is in extremely bad condition (looks wise). There are tons of calcium stains all over, from some being inside of the light fixture, to most being on the rim of the tank and also on the inside glass in various spots on the tank.

What products would you recommend that would remove this and not damage the tank or the silicone?

I was going to try using CLR on it, however I'm slightly worried that it will eat away at some of the silicone and I personally don't really want to reseal the whole tank. I also was going to try using Vinegar first, however I'm not sure how effect it will be at removing the calcium since in some spots you can barely see through the glass (yeah, it's that bad), even with using a toothbrush or a sponge to scrub away at it for awhile.


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## SueD (Nov 20, 2010)

I think vinegar works well. Lay the tank on its side if you have to and let the vinegar sit on there for a while. Just rinse thoroughly when done.


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## Bushkill (Feb 15, 2012)

SueD said:


> I think vinegar works well. Lay the tank on its side if you have to and let the vinegar sit on there for a while. Just rinse thoroughly when done.


Yup. I'll just add that if it's really stubborn, soak a wad of paper towels in vinegar and let it stand a little longer. The towels will just let you cover some spots where it's tough to let it stand in vinegar, like rim corners and the rim itself and allow a longer soak time. Use white vinegar.


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## tweetyfish (May 12, 2014)

Are you sure it's not some hard water spots? If so I have used Bar Keepers Friend in the liquid bottle. It worked pretty good for me when I changed my 180 gal from salt to fresh.


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## philipraposo1982 (Mar 6, 2014)

vinegar is good and works great. but you need to soak it for a while.


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## PlantedRich (Jul 21, 2010)

Something not mentioned might be in play. There are times when the hard water may have effected the glass. There are times when I get the deposits off but the glass is still not clear. I have had tanks that never came clear. 
Just something to make you worry? Sorry, Just be aware and don't think it is something you are doing wrong if this should happen. 
I use vinegar on most things but there is also a product (Acid Magic) which is a safer form of acid which I use for the really crusty stuff. Still somewhat dangerous, though. Read the label carefully if you should go that way.


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## KnownSyntax (Mar 15, 2014)

SueD said:


> I think vinegar works well. Lay the tank on its side if you have to and let the vinegar sit on there for a while. Just rinse thoroughly when done.


Sadly I forgot to mention that it's a bowfront, but using the towels to let it soak would work.


tweetyfish said:


> Are you sure it's not some hard water spots? If so I have used Bar Keepers Friend in the liquid bottle. It worked pretty good for me when I changed my 180 gal from salt to fresh.


It's honestly a mix, although my family owns a pool and it's mostly the calcium that is the biggest issue compared to the small traces of limestone, etc. found in hard water.


PlantedRich said:


> Something not mentioned might be in play. There are times when the hard water may have effected the glass. There are times when I get the deposits off but the glass is still not clear. I have had tanks that never came clear.
> Just something to make you worry? Sorry, Just be aware and don't think it is something you are doing wrong if this should happen.
> I use vinegar on most things but there is also a product (Acid Magic) which is a safer form of acid which I use for the really crusty stuff. Still somewhat dangerous, though. Read the label carefully if you should go that way.


I'm hoping this isn't the case and I'm already somewhat worried about that. Although I've been able to remove it from glass-like substances, just took more effort and using a hard material to rub it off (which I don't even want to try with a fish tank since I know it would damage the glass/acrylic right away).

Thanks for your guy's replies, I'll try to use vinegar and just scrub the heck out of it and see how it goes.


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## PlantedRich (Jul 21, 2010)

Watch out with too much rubbing! 
Depends on what the hard spots are made of but if it is gritty stuff like ground up limestone, it can scratch while rubbing too hard. For the really tough stuff there is a tool made for the job. It is designed to take paint off windows and really has little chance of scratching a glass tank if done right. A paint scraper with a good new blade is very simple. The mistake some make is trying to reuse the same blade which has rusted and has pits. Those can scratch glass as they are not smooth. The second point to watch is when you get near the silicone. The blade will easily lift the silicone so watch so you don't get too close. Running parallel to the silicone helps.


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## nonliteral (Aug 20, 2012)

I've had very good luck removing light calcium stains with Mr. Clean Magic Eraser -- it doesn't seem to scratch glass (unless you drag a piece of gravel with it, etc.) and doesn't appear to leave any undue residue in the tank - it particularly works well on the "just can't get them clear" areas. I've used this in the past on reef tanks and it's now my go-to on my tanks and calcium spotted glass on vivariums with misting systems.


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## KnownSyntax (Mar 15, 2014)

Here are some of the photos of the beforehand looks. I'm not sure what type of water nor the storage conditions of the tank before I got my hands on it, but it's obvious that they didn't really care that much about it at all. The tank may look small but it's a 28 gallon euro bowfront tank made by Marineland. Sadly, the top glass part cracked in half right as I was just starting to lightly scrub it so I'll have to order another one after I get this fully cleaned. The brown stuff on the rim and slightly in the tank is when I was removing the sand (very, very fine grained) that was slightly mixed with soil of some types as I was checking to make sure that there were no leaks and it was all sealed up (which it is).

I'm not so sure on the lights or how many watts they are, will have to check when I replace them after attempting to clean the lighting fixture along with the tank later this week.



PlantedRich said:


> Watch out with too much rubbing!
> Depends on what the hard spots are made of but if it is gritty stuff like ground up limestone, it can scratch while rubbing too hard. For the really tough stuff there is a tool made for the job. It is designed to take paint off windows and really has little chance of scratching a glass tank if done right. A paint scraper with a good new blade is very simple. The mistake some make is trying to reuse the same blade which has rusted and has pits. Those can scratch glass as they are not smooth. The second point to watch is when you get near the silicone. The blade will easily lift the silicone so watch so you don't get too close. Running parallel to the silicone helps.


Some parts it feels rough, some parts it doesn't. I haven't fully removed all of the other "gunk" from the glass or the rim at all yet, however from me rubbing on it with a light effort on the rim it seems like it just peels away, although not so much on the glass. It's more of the calcium you see built up (well in AZ that is) on the tiles if you own a pool. I haven't tried vinegar yet as I'm wanting to do this all in one go with more room, so I'll be waiting later this week to try it all out.
I'll have to try that tool (I know exactly what you are talking about) if it still feels like a rough feeling after putting vinegar on it and letting it sit for a few minutes or more.



nonliteral said:


> I've had very good luck removing light calcium stains with Mr. Clean Magic Eraser -- it doesn't seem to scratch glass (unless you drag a piece of gravel with it, etc.) and doesn't appear to leave any undue residue in the tank - it particularly works well on the "just can't get them clear" areas. I've used this in the past on reef tanks and it's now my go-to on my tanks and calcium spotted glass on vivariums with misting systems.


This tank is completely empty, so I'll try that if vinegar doesn't work. I'm not sure if it'll be able to make these spots however clear, since it honestly looks like years of not fully filling a tank up or cleaning the glass whatsoever. Do you still think that it could clean it if vinegar doesn't work, or are your buildups less then what I'm left with cleaning?


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## jhays79 (Mar 28, 2012)

That looks to be in similar condition as the 20g high a friend gave me. I had it soaking with a gallon of vinegar and filled the tank with water and let it sit for a week. The vinegar did nothing to break down the calcium deposits. Let us know how you make out. I'm gonna give a Magic Eraser a try and see if that helps.


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## tweetyfish (May 12, 2014)

Looks like there could be some hard water etching in the glass. Hope not. If it is not all is lost because after you get the deposits off and you get water back in it will be hard to see. I had the same problem on my 180 and you can't see any after filling.


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## PlantedRich (Jul 21, 2010)

Looks like the normal used tank I find here on Craigslist. They are a bargain but it does require time and effort. 
I find vinegar has to be used full strength to soak into those deposits. They are mostly calcium from limestone. You can get the really rough stuff off by scraping. A putty knife for starters and then I move into the vinegar with putting it on with an old brush. I have the jug of Acid Magic to get into the cracks and really do a much quicker job but it does have to be handled very carefully. If you don't get it rinsed well a residue can stay around the top rim and crash your PH every time you top off. Never mind how I found that ! 
Pool supply stores for cleaning tile if you get down to that? I recommend it but with care.


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## Diana (Jan 14, 2010)

Here is how I dealt with that in the past. Glass tank with plastic trim and lid. Wear gloves! Though these are both food materials they are still highly acidic, and will burn if you have any cuts on your hands, and you do not want them in your eyes!

1) Do a reasonable job with a razor (the paint scraper is a good idea, too) and rinsing. It will get rid of a lot of it. Be very careful scraping the plastic, the razor will cut the plastic. Do not get it near the silicone. When using it on the bowed front hold the blade so the sharp part is vertical and work in strokes that are parallel to the arc. 
2) Dampen the remaining white areas with lemon juice. Sprinkle on Citric Acid, which is found in grocery stores, perhaps with the name Sour Salt. 
3) Wet a paper towel with lemon juice and cover the white areas. Keep the towels damp. 
4) About every 15 minutes try scraping some more. 
5) After about 3-4 times figure that you have loose all the easy to get stuff and figure out a way to keep things soaking a lot longer.


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## nonliteral (Aug 20, 2012)

(re: "Magic Eraser")



KnownSyntax said:


> This tank is completely empty, so I'll try that if vinegar doesn't work. I'm not sure if it'll be able to make these spots however clear, since it honestly looks like years of not fully filling a tank up or cleaning the glass whatsoever. Do you still think that it could clean it if vinegar doesn't work, or are your buildups less then what I'm left with cleaning?


I first ended up trying the magic eraser after vinegar wasn't working for me, so it's worth a shot. You want to do it with the sponge ("eraser") really wet, and rinse it often as you go.


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## KnownSyntax (Mar 15, 2014)

As an update I only used vinegar (white distilled, so 5% of the acidity strength), and a bathroom brush that I thought would be helpful along the way. I did pick up a magic eraser but did not use it yet.

I was able to just use a spray bottle I bought and filled it up with vinegar, and then just sprayed on the rim and scrub it out. The rim honestly took me probably 30 minutes just to get it 98% clean (there are still some spots in the very corners, although they aren't really noticeable unless you are looking directly for them). I then did just the same way to spray the vinegar onto the glass (on side at a time) and then just scrub away (didn't really let it sit). I did this twice, then would use the garden hose to spray it down, and repeated. This was done about 3-4 times overall, and when the tank was filled was water it looked brand new.

There was still a frosty look to the glass after this, so I thought "Maybe it's somehow on the outside too?" so I did this same thing I did for the inside to the outside of the glass with vinegar 2-3 times. 98% of the calcium was removed from the glass, minus a few selected spots on the side glass where it seemed to have etched the glass as it is smooth rather than rough like before.

With only 1/4 of the vinegar left that I bought in the spray bottle left, I did half of the lighting fixture. What got me as odd is the second I sprayed it onto the calcium on there, it made a LOUD fizzing/cracking noise and the calcium literally melted/disappeared. I'm not sure what type of reaction this was, but maybe on the lighting fixture it wasn't calcium but something else to make the vinegar react that strongly to it?

I'm going to try to use the magic eraser and see if I can remove those (what appear to be etched but I'm not going to be 100% too sure about that) spots on the top sides of the tank. 

Thank you guys for helping me use vinegar because honestly I wouldn't have ever really used/thought of using it to clean a fish tank at all.

I've attached the photos of the tank emptied and along the way, although the one side shot photo it's hard to kinda see how the glass is frosty looking unless you view only the photo (phone photos, best I could do for now). What gets me is that if there is water there you can't see the frost whatsoever. I'd try to use more vinegar but I used a full bottle of it before I saw this spot, hoping the magic eraser will do the trick.


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