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I'm posting a question here for my boyfriend. His 20 gallon tank is starting to succomb to hard water depoists--ya know, it's that bad white material that seems to calcify over any source of water (the faucet, teh bathtub drain, etc).

Unfortunantly, it's b/c of the part of the country we're in (the Midwest) so all teh tap water comes out with more mineral in it that deisred. I know buying bottled water can be a solution, but that's just too much to get for every refill or water change.

So, does anyone here know how to remove hard water diposits from tanks safely without harm to the fish? And how do you keep it from coming back?

-Silver

Hi,
If the part encrusted can be removed from the tank, clean
it with a plastic scrubby and vinegar. Vinegar is a weak
acid and it will break the carbonate bonds and clean the
piece. If it cannot be removed, a safety razor blade
and some elbow grease is the next in line. I would not
use any chemicals in the tank.

You can eliminate the problem by using a mixture of tap
water and either RO water or DI water. Once you mix the
waters and get the desired pH and GH and KH, then remember
the mix (1 part this, x parts that) and use that ratio when
changing the water. Because of the costs, I would only
change 10% of the tank a week, stock lightly, and feed
sparingly.

Frank


-->>> The Confidence of Amateurs, is the Envy of Professionals <<<--

First you have to ask yourself what kind of hardness is present.

'Hardness' is a term that covers high dissolved mineral concentration without being too specific as to the actual chemical composition.

Generally, 'temporary' hardness refers to carbonate type minerals (in particular calcium and magnesium hydrogen carbonate), and 'permanent' hardness refers to calcium and magnesium sulphates among others that are more soluble than the carbonates. Calcium and magnesium chloride can also feature here - these two minerals are VERY soluble in water, so they won't in general leave deposits.

The carbonate minerals are called 'temporary' hardness because they can be removed by heat. They are the cause of the so-called 'fur' on the inside of kettles. They can be dealt with chemically in two ways. One, by increasing acidity, and two, by increasing alkalinity and forcing a precipitate to form. However, doing this in a fish-safe manner is likely to be a challenge to put it mildly even if you're au fait with chemistry.

First, the acid route. Titrating your water with dilute nitric acid will result in the formation of calcium and magnesium nitrate. Nitrates, of course, are produced by your filter bacteria, and are absorbed by plants. Magnesium nitrate in particular will benefit your plants doubly, because magnesium is the metal that exists in the centre of the chlorophyll porphyrin molecule.

However, you can't just add nitric acid and hope you've eliminated the minerals. One, you won't eliminate them, you'll just change their chemical form, and two, you need to balance the reactants in the reaction precisely, which calls for titration skills. Which you need to do each time in order to establish the concentration of the respective carbonate minerals in your water so that the amount of acid can be precisely metered to match. Because excess nitric acid isn't something you want floating around an aquarium.

You could use a different acid, but that complicates the picture considerably. Especially if you use an organic acid. However, peat filtration is one means of using complex organic acids to demineralise water which is pretty effective over time, and has the advantage that it occurs in natural watercourses too, particularly those in Asian peat swamp forests. However, this is only applicable if you're intending to keep fishes that like acidic conditions (e.g., Discus, South American Dwarf Cichlids) or you're trying to breed fishes that need acidic water for breeding (Harlequin Rasboras, Cardinal Tetras etc).

The second route involves increasing alkalinity and forcing the formation of carbonate precipitates. Calcium and magneisum hydrogen carbonate are relatively soluble, but calcium and magneisum carbonate are less so. Forcing the equilibrium toward carbonate precipitation requires increased alkalinity. Trouble here being that the amount of precipitate you'll get is fairly small, and you have all the fun of filtering it out.

An expensive but more convenient way of achieving the same end result is ion exchange resins. These, however, have their own maintenance issues - relatively short useful life before recharging needed being one of them. Plus the capital expense is considerable.

However, you may be able to deal with the problem at source. Take a look here and take a look at their water hardness removal system for tap water. OK, the company is based in Denmark, and so availability could be a problem, but they market internationally AND have an ISO 9001 certification in the UK (in other words they pass stringent quality and safety tests). So it might be worth chasing this up. Not sure how their system works, but apparently it does. Give it a whirl and see ...



Panda Catfish fan and keeper/breeder since Christmas 2002

Hm. A lot of this really sounds out of his league (at least chemically speaking). It would definitly run too expensive to try to chemically alter the water and it's minerals, and I'm pretty sure in the ion thing.

I'm guessing its calcium build up, maybe with some lime? I'm not sure about his water as much as I know about mine...it's strange in itself...my best overall guess is that there is no filtration system on his apt's water supply, so everything from the tap comes out hard.

I did hear about using vinegar to help aid in removing the water hardness, but I don't know the effect it would have on his fish (they're community fish, with a few tiger barbs, and a couple kuhli loaches). He plans on removing his cichlids from their smaller tank and donating them off, and then moving his fish in the problematic tank over to the newly emptied tank while he cleans...I think. In whatever case, he will need to be able to clean the tank after he puts fish in it again, and be able to keep the deposits at a manageable level.

He's purchased some steel-wool and plans on trying that out, but I know that will rust when it comes in contact with water and will eventually break apart. So, elbow grease seems to be the only other alternative. based on what you've said Frank, I think that may be the easiest way for him, but I'm not sure about the RO or DI water. Will just keep working at it be enough? Or will it eventually just get so hard on it won't be possible to remove the deposits?

It's calcium carbonate. Which is also what limestone is made up of and something we have tons of in the midwest. Vinegar is the simplest solution. Don't get tons of it in the water but if some drips in it's not an issue. It's completely harmless to fish except for the fact that like all acids it can lower the ph. With the amount of buffer in the water though it would take alot of vinegar to move the ph. You can wipe equipment while it's running and the edge of tanks without worry unless you decide to dilute your water alot with RO or distilled. I also use vinegar to rinse tanks between use, wipe off the glass covers about monthly, and every few months I pull the impellers from my filters and soak them in a cup of vinegar for a few hours. You can also soak the filters in a bucket with 50/50 vinegar and water. However if your going to have your filter not running for awhile either have a backup filter to put your media in or at least some aeration for the tank and replace any media that does not have aerated water running across it for more than an hour.

It's not necessary to soften the water since the fish will adapt fine to it and the deposits are not harmful but the easiest and safest way to avoid the hardwater deposits is to dilute the tank water with distilled or RO water. You can get RO refills for $.25/gallon from many grocery stores and Walmart. You don't have to replace all the water and should never use that type of water by itself but mixing in around 25-50% RO or distilled depending on your exact water parameters will help considerably with hardwater. Peat moss only has a moderate effect on water that hard and usually despite chemical filtration the water will turn black from the tannic acid before you manage to soften it any. Peat is a good secondary way to soften the water further after you've diluted it some.

Hi,
I was not even suggesting that you pour vinegar into
the tank with the fish! I said the "removeable parts."

I've never heard of adding vinegar to a tank. I can only
imagine dead fish nearly instantly.

Cleaning the crust off of the heater, tubes, hoses,
etc it works great. I use vinegar on the glass hood
where the water splashes and evaporates leaving behind
a carbonate crust. But, I do it over the sink where I
can rinse the glass off, not on the tank.

Frank


-->>> The Confidence of Amateurs, is the Envy of Professionals <<<--

Actually you can pour some vinegar into the tank and it probably won't kill the fish provided your water is buffered well enough. I've heard of some people doing it. I wouldn't suggest doing that but it's pretty safe stuff. Unless I really want to soak something I frequently wipe things off without removing them from the tank.

Lol Frank, I didn't mean that! That's why I suggested moving the fish to the other tank while the first gets some vinegar and scrubbing action. I didn't mean to imply to soak it with the stuff with the fish still swimming about, slowly turning into pickles!

Ah ha...Sham's from my neck of the woods (I'm in NE)...so that's what it is? Hmm...okers...I'll pass this info on to him.

Any other tips or tricks out there from ya'll on this issue? I know I've already gleaned tons of stuff from ya, but the more knowledge the greater the power!

-Silver