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FAQs on Total Dissolved Solids, Minerals, Calcium... in Freshwater

Related Articles: pH, alkalinity 1, In praise of hard water; How hard, alkaline water can be a blessing in disguise by Neale Monks, Treating Tap Water, A practical approach to freshwater aquarium water chemistry by Neale Monks, The Soft Water Aquarium: Risks and Benefits by Neale Monks, Freshwater Maintenance, Treating Tap water for Aquarium Use

Related FAQs: pH, Alkalinity, Acidity 1, pH, Alkalinity, Acidity 2, pH, Alkalinity 3, pH,  & FAQs on: FW pH/Alkalinity Science, pH/Alkalinity Measure, pH/Alkalinity Adjustment, pH/Alkalinity Products, pH/Alkalinity Anomalies/Fixing, & Water Hardness, Freshwater Aquarium Water Quality, Treating Tap Water for Aquarium Use, Freshwater Algae Control, Algae Control, Foods, Feeding, Aquatic Nutrition, Disease


TDS increasing      10/13/15
Dear WWM,
Thanks a lot for this wonderful service.
My tap water has TDS 250 ish and the commercial RO water I buy in bulk has it as 47-48.
<Mmm; you likely know... should be about zero>

I mixed them using the Pearson's square to get a value around 90. By the way the KH was 3 German degrees. I have Rams and Cardinals.
River gravel topped with silica sand in substrate. pH 7.2 but should drift lower with plenty of Indian Almond leaves and immersed roots. I am vying for that tea coloured look with floating plants.
<I see>
10 days after water change the TDS was 118!
What is causing this to increase?
<Some source... most likely the river gravel. I'd put a handful of this in some RO water in a container... and test the TDS every few days>
Is it the substrate leaching ions even in this neutral to alkaline water and should I be bothered?
<Is probably the substrate, and I would not be overly concerned. I'd be "cutting" your new/make-up water with a higher proportion of RO to balance this>
I have not added any additives or fertilizers. Have fed with freeze dried blood worms, Tetra bits complete
and Hikari micro pellets.
<These only slightly add to dissolved solids>
Only topped up evaporation loss with same RO
water. Unfortunately I do not have a GH test kit which might have cast some light.
<Cheers, Bob Fenner>
Re: TDS increasing      10/13/15

Dear WWM,
Thank you for your inputs. I shall definitely try the experiment.
Unfortunately in my part of the world, what comes 'sealed and branded' is taken in good faith, an attitude that purifies everything, including RO water.
<Ahh; not so different here (US)>
Its only the rarest minority like me, armed with a TDS meter, that receives a different version of truth! But I digress :)
<Thank you for sharing. BobF>

Aquarium Question: Over-abundance of calcium/minerals in tap water?  6/13/10
My name is Jessica, and I just have a quick question for you.
<Fire away.>
I have an aquarium and will soon be moving in to my fiancé's house. The problem is, the water at his house has a lot of calcium and mineral deposits in it. It is well water (as is mine), and I guess his must come from an area in the ground with a lot of rocks near it or something.
<I see.>
I am just concerned how his will affect my tank when I do water changes and that it will build up in the filter and/or harm the fish.
<Minerals will not "build up" as such; the hardness of the water will stay more or less constant all the time. But excessive hardness can be bad for soft water fish. It may not kill them, but it can reduce their hardiness and lifespan, so it does make a difference. Best to choose species adapted to hard water: livebearers, Rainbowfish, etc.>
Obviously, I don't think that it is possible to do water changes straight from the sink.
<Sure it is. In fact you want to avoid water from a domestic water softener. You want the unsoftened water from the drinking water tap.
Domestic water softeners replace hardness with sodium salts, which are as bad for your fish as they are for you.>
I was just wondering if you have a safe product or method or anything that you would suggest for this problem.
<In all likelihood mixing unsoftened tap water with RO or rainwater 50/50 will do the trick nicely. This won't be necessary if the hardness is no higher than 15, maybe 20 degrees dH. But if the hardness is above 20 degrees dH, and the pH is 8 or higher, you really shouldn't maintained your soft water cichlid and catfish in such conditions. Will significantly shorten their lifespan.>
Also, just to let you know, I have a small Oscar (about two inches) and a larger (about four inches?) Rhino Pleco, or Alligator Pleco.
<All soft water fish.>
They are currently in a 45 gallon aquarium with a Whisper 30-60 HOB filter.
<Obviously you will need an aquarium about three or four times this size for these fish once adult, and a hang-on-the-back filter isn't even remotely adequate for fish that produce as much waste as adult Oscars or Loricariid catfish.>
If you have any advice please let me know.
<Do read:
Thank you for your time,
<Cheers, Neale.>
Re: Aquarium Question: Over-abundance of calcium/minerals in tap water?  6/13/10
yes, when I said "build up" I meant like as a solid. our shower gets white build-up in it very quickly from the calcium.
<You will see this where water dribbles out of the tank, for example if the filter splashes water, and so lime builds up inside the hood. But nothing serious that can't me removed periodically with a bit of vinegar or lemon juice. As for the water itself, no, calcium carbonate and other minerals don't accumulate in the water over time: what you take out during water changes is matched by what's put back in.>
in order for us to be able to drink it we actually have a separate spout with a reverse osmosis unit, and we buy those huge jugs of drinking water (like for the water coolers) for our dogs. the water tastes really bad.
<The taste may not be likeable to you, but the water is certainly potable, and for the right types of fish, actually preferable. A wise fishkeeper chooses species that appreciate local water chemistry. If you have "liquid rock" as we call this sort of water in England, then livebearers, Goodeids, hard water killifish, Central American cichlids, Rift Valley cichlids, Goldfish and brackish water fish would all be very sensible choices. All of these would positively thrive in the water conditions you have. Keeping fish like Oscars and Loricariid catfish that require different water
chemistry to what you have is creating a rod for your own back. With plain tap water they'll never be happy, and mixing the tap water with RO or rainwater -- which is what you will probably need to do -- will be expensive and/or a hassle. But without knowing your precise what chemistry, i.e., pH, general hardness and carbonate hardness, anything I say here is speculation, albeit informed and intelligent speculation.>
and yes, I'm looking into purchasing a one hundred gallon tank in a month or two (right now they're teeny-tiny in the tank they're in), and a canister filter, or making my own "separate tank underneath" filter (sorry, I forget what they're called at the moment).
right now I do 50% water changes at least once a week, along with vacuuming the bottom. like I said, they're both still very small right now.
<Fine. But Oscars grow very fast!>
also, I didn't realize that the Plecos were considered catfish...learn something new all the time I guess. :]
<Yes they are. In fact they belong to the Loricariidae, the biggest family of catfish, with some 800 species.>
as for the hardness of the water, I can't test it right now, but I'm pretty sure it's not suitable for them...as I said, it tastes awful.
<Taste has nothing to do with. You really do need the numbers. Tannin-stained soft water from the Rio Negro tastes pretty horrid, like swamp or a overbrewed cup of cold tea. But Amazonian fish love it!>
also, they do have to add some sort of salt softener in order to make it that useable.
<Precisely. Do not use this for the fish, and don't drink it either. The drinking water tap in the kitchen is probably not connected to the domestic water softener.>
so as you said, the salt's no good. thank you again, and please email me back if you have further suggestions. I'll have to look into bringing water from my mom's house across town for my changes.
it's nice soft water (very delicious well water, not like this other stuff), and they've been doing very well in it.
<As expect. But conversely, hard water fish like Mollies and Goldfish would not do well in the soft water, and would love the hard water you have in the new house. It's all about horses for course. Instead of Oscars for
example, and pair of Nicaragua cichlids or a big Jaguar cichlid would be a great alternative. Just as pretty, but much more at home in liquid rock.
Actually, your Rhino Plec (Pterygoplichthys scrophus) should be okay in hard water; most of the other Pterygoplichthys species do okay in liquid rock, even if they don't actually prefer it. I've certainly kept Pterygoplichthys gibbiceps and Pterygoplichthys pardalis in hard water Central American cichlid aquaria.>
and I'll be sure to read that article (right now). thanks again,
<Cheers, Neale.>
p.s. -- sorry for no caps. I'm writing from my iPhone and it takes long enough to type as it is
<You're forgiven. Cheers, Neale.>
Sent from my iPhone
<Cheers, Neale.>
Re: Aquarium Question: Over-abundance of calcium/minerals in tap water?  6/13/10
Okay, thank you. Again, I already have and have had the fish and suitable water for them, so it's not a matter of "getting" fish that are suitable to the new water. These are my fish and they come first.
<Fair enough.>
The drinking water in the kitchen really isn't a spout..it's a tiny spigot, not even large enough to fill the dog bowl when it's empty [about a gallon maybe?]. It would definitely not do for water changes even in a five gallon tank.
<If you have domestic water softener, of the sort used to remove lime from the water so appliances don't "fur" up, then somewhere there should be tap that doesn't connect to the softener. A tap that bypasses the water softener. Certainly here in the UK that is absolutely standard and I believe a legal requirement. Certainly you shouldn't drink water from a domestic water softener, which is why it's normally the kitchen sink tap.
Wherever this tap is, that's the one you use. If the one in the kitchen is too small, then check the one in the garden for the hosepipe. If it isn't clear, there are two reasons you don't use softened water. The first is the sodium chloride added to it. The second is that it has zero carbonate hardness, which means that it is very unstable in terms of pH.>
I will have to keep some of the large water jugs from the dogs and fill them up at my mom's. That shouldn't be a big deal. And again, just to clarify, I know that the minerals won't "build up" in the sense that you keep assuring me that they won't [like, accumulate in the actual water, I guess].
I just meant the physical, solid build up [again, I'm not trying to be, like, rude or snotty or anything, just letting you know. Sorry if it sounds rude].
<As I said, yes, you can get lime scale where water from the tank splashes onto something, like the hood, and then drips or evaporates away, leaving the lime scale behind. But otherwise no, you won't get chunks of lime scale forming inside the aquarium, filter or anywhere else under the waterline.>
Anyway, thank you again and I'll be sure to make accommodations for them.
<Cheers, Neale.>

Re: Aquarium Question: Over-abundance of calcium/minerals in tap water?   6/14/10
hi again. sorry to be annoying, but I seem to have somehow lost the link you originally sent me and I'd like to keep track of it for reference.
<This one?
would you please be able to send it again? sorry again..
<Cheers, Neale.>

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