Reverse Osmosis for softening water

I hope its ok to "bump" this into a new thread - the other Water question thread has taken a different direction!

I've tried to research it as much as possible myself, but am looking for reassurance from someone far more expert than myself . . .

Basically, I'm about to have to replace the entire filtration system on my well, so I'd like to do it right this time.
I recently discovered (courtesy of some of the fine members of this forum!) that my softened water is not soft and in fact has just exchanged calcium ions for sodium ions.

I was going to install a tap direct from the well, before any filtration takes place, for use for hardwater. The water contains a fair bit of manganese and iron, as well as calcium. Is this likely to be OK for hardwater species? or is there a downside to the other extra minerals?

I was also considering adding an RO filter, and then mixing RO & untreated water to get soft and/or low pH water - assuming I can sort out the proportions through trial and error.

Does this sound viable or am I being too simplistic?

Many Thanks

Jim.

Jim, I had a reply ready for you on the other thread….but the human health bit came.

Regarding your present softener, standard water softeners will, as you’ve been told, exchange the calcium (and magnesium) ions in hard water with sodium ions. Rigorously, the water will be ‘soft’ (ie it will not be hard to obtain a lather) but it will contain sodium instead of calcium.
(Of course I am presuming that the water softener is a sodium aluminium silicate based or styled system).

In short, irrespective of whether or not the water comes out soft, those types of ion-exchange resins do not produce water suitable for use in aquaria in general (fine for washing clothes and your hair).

What sort of ‘hardwater’ species are you considering as some so called ‘hardwater’ species are not specifically ‘hardwater’ fish at all (but may be high-pH-water fish).

I’m interested in the manganese content of the water? Tell me more (eg the content of manganese, and pH, salinity)
And what is the magnesium content….as that is important in some fish water.

ian

Hi Ian,
Many thanks for the response.

I'm hoping to keep fish from the African rift lakes, especially Victorians. Would also like to keep geophagus and some others which clearly need completely different water parameters.

I'll try to dig out the original lab report, but calcium, iron and manganese are at quite high levels (unfit for human consumption. ) Ph was high as well. No idea about magnesium, it wasn't at a level to cause concern.

I'm willing to go to reasonable lengths to treat water suitable for fishkeeping, but I'm afraid my raw material is making it difficult if not impossible,

Jim

Hi Ian,
the values are as follows:

pH = 7.3
Conductivity (uS/cm at 20C) = 579
Nitrate & Nitrite = 0
Calcium (mg/L) = 132
Iron (ug/l) = 5228
Zinc (ug/l) = 17
Manganese (ug/l) = 201
Turbidity (NTU) = 85.5

No results for magnesium.

The well technician can povide me with taps before all filtration, after main filtration but before water softener and an additional seperate supply which goes through RO after all other filtration.

Thanks again,

Jim.

RO is a good option to start work to get what you want.
I'm not sure what is available off-the-shelf in your area to 'make' water of given conditions, but something will be available to get you started. Mixing with your water supply may also be an option...depending on what you have and what you need.

Well buffered and stable water is a key element.

ian

Thanks again Ian.

I'm going to insert a tap in the system, after the main filtration has taken place, but before the water softener. This means that I'll be diluting calcium rather than sodium with my RO water, which I beleive is the best option.

This leads me to one last question (I hope I'm not imposing too much) which I suspect is right in your area of expertise:

The UV has to come after the softener on the main system. Although no bacteria were found in tests on the water, I included a UV just in case it ever gets contaminated. The water I'll intercept for my tanks won't have gone through this. If I get E.coli or similar nasties in there, will the aquarium filters be a superb place for them to multiply?

Jim.

Thanks again Ian.

I'm going to insert a tap in the system, after the main filtration has taken place, but before the water softener. This means that I'll be diluting calcium rather than sodium with my RO water, and the iron and manganese will be gone - which I beleive is the best option.

This leads me to one last question (I hope I'm not imposing too much) which I suspect is right in your area of expertise:

The UV has to come after the softener on the main system. Although no bacteria were found in tests on the water, I included a UV just in case it ever gets contaminated. The water I'll intercept for my tanks won't have gone through this. If I get E.coli or similar nasties in there, will the aquarium filters be a superb place for them to multiply?

Jim.

Jim,

I must apologise as I wrote my last post before you posted the water parameters list, and then posted it without reading your post.

I haven't had a good look at your readings as I've just awoken after a late night workings (and my eyes are blurry)

For Lake Victoria, I would not look at present water quality analysis and then try to emulate it...Lake Victoria has turned into a bit of a sewer.

Lake Victoria contains, generally, less of the usual sodium/calcium/magnesium/bicarbonates etc than either Malawi or Tanganyika.

Calcium concentration is, however, much of a muchness between them lakes (I would, however, call lake Tanganyika a "magnesium lake" as it's magnesium conc is much much higher than Malawi or Victoria).

Silicas (dissolved), however, are much higher in victoria than in malawi or tanganyika. Interesting.

The calcium conc from the well looks....well...much higher than any of the lakes (between 3 and 20mg/l would be the ranges between the lakes, calcium levels within a lake vary within the lake as well).
Is the well slaked? (limed?)

You would be better aiming somewhat for a Malawi-type water.
I don't know if places sell 'Victoria' salts or not.

If you get some off-the-shelve rift valley salts (maybe someone here can recommend a good brand as I I've never used the off-the-shelf rift lake salts....), then they would address the magnesium.

You need magnesium in the water.....(not as much as in Tanganyikan water) but it needs to be there.

I sound like a stuck recorded parrot....but the pH and other water parameters must be stable.

pH is one of the biggest areas that I see.....whilst you need to aim at the correct pH, getting an exact pH is much less important than getting a stable pH within the expected range of the water.

The water needs to be well buffered....and that is something that is very much important with the rift lakes.

Now, here is a challenge...silicas....do you need to emulate victorias silicas or not? what is the actual importance of them to the fish? is it a waste of time to try to emulate them?
I don't have any answers there....but I do have the questions.

Bacterial content....that is why I was interested in your manganese levels. Manganese bacteria are like the iron bacteria....pains in cloking things up.
I'm not sure off-hand the manganese levels in victoria (it would be very sad for anyone to start remembering all chemicals in various waters)....maybe someone can have google that for us.

I wouldn't like to comment on whether or not you'll end up with a bacteria problem in your tank from your well....but if the water is fit to drink, then the bacterial content should be fine for fish.
I'm also not sure that e.coli is the main thing to worry about either.....there's worse to behold.

As for whether a low output UV lamp will do anything against a specific species of organism is another topic of debate. The effectiveness of UV depends upon the actual wavelength of the UV, the output power, the distance from the water, the time that the organism is exposed to the UV, and the organism itself (and whether or not you're trying to zap anyhting that forms cysts), and, of course the concentration of the organism.

Best wishes with the Victorian fish....I was once getting into lake victoria fish, but only a few known species came from victoria in them days.

Now, I need to have another cup of coffee and get properly dressed and feed some animals (and possibly pop out to a few LFS just off the M50)

ian

Hi Ian,
looks like I'm better off abandoning the well and starting off with RO water and adding what I need to it.

Many Thanks for all the advice.

Jim.