# Water filter/softener (regeneration salt) and water for planted aquarium



## arcturus (29 Nov 2021)

Hi!

A water filter/softener is going to be installed in the next weeks in my building to reduce water hardness (currently ~14°dH). I will have no way to bypass the system, so all the household water will come through the filter. This filter uses regeneration salts and replaces substances such as magnesium and calcium with sodium. 

What should I do in order to make the softened water appropriate to a "high-tech" planted aquarium (moderate/high plant mass, shrimps, and low fish load)? Can I use this softened water as-is or should I get a RO system to demineralise the water and then re-mineralize it with a GH/KH mineral mix before adding it to the aquarium? Any way to prepare the water without RO? I am trying to avoid the RO route because I it will be a challenge finding a place for the RO water tank (I need ~100 litres/week). Thanks for the input!


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## hypnogogia (29 Nov 2021)

You shouldn't use it.  Back in the day I used water softener water thinking it would be OK, but I had real problems growing plants and always suffered form lots of algae.  Moving to rainwater changed this almost overnight.

I'd check with them as the advice is usually that sferehnt water should bot be used as drinking water.  I think you'd have a legitimate concern and should be able to ask that they provide a drinking water tap.


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## dw1305 (29 Nov 2021)

Hi all, 


arcturus said:


> so all the household water will come through the filter.


It isn't ideal, there are definite health issues (because of the raised levels of sodium (Na)) and the water tastes horrible. 

We have <"a softener"> with a spur off the rising main to provide drinking water.  Our tap water is hard (18dGH /18 dKH), but <"straight out of the limestone"> and it tastes lovely, but if for some reason you end up with a glass of softened water you will spit it straight back out, it is vile. We also get through a lot of salt. 


arcturus said:


> Can I use this softened water as-is or should I get a RO system to demineralise the water and then re-mineralize it with a GH/KH mineral mix before adding it to the aquarium?


Unfortunately RO (or rain water?) unit is your only hope. 

cheers Darrel


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## ian_m (29 Nov 2021)

arcturus said:


> I will have no way to bypass the system, so all the household water will come through the filter


This is severely not recommended under the water supply regulations 2000 in that softeners add sodium to the water. Softened water must not be used to feed babies (and possibly children). Generally there should be a unsoftened water tap available for drinking, cooking and obviously fish water, usually in a kitchen.
FAQs - UKWTA

I have a whole house water softener and the cold taps in the kitchen (and two of the bathrooms) are unsoftened water. Also two of house toilet cisterns are hardwater so as to try and reduce water softener salt usage.

Also do your water softener research, as some use salt at quite a prodigious rate and seeing price of salt is directly proportional to gas prices, it can make a hell of a cost difference. Make sure softener is metered so only recharges when resin tanks are exhausted.

My softener is a Twintec and despite using more expensive (but considerably easier to handle) block salt, it cost less to run than my previous salt tablet softeners. Also comes with 10 year guarantee as both previous softeners I had failed soon after their 3 and 5 year guarantee ran out !! DO NOT get a softener with any electronics in whatsoever, electronics, salt and water do no go together and in my experience do not last very well. Current Twintec, which is purely mechanical (no electricity at all) had issues after 9 years, was repaired under warrantee and got another 10 years (until 2027 in my case, so that's 19 years guarantee !!).

From the "great but no longer exist Sceptical Aquarist"


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## arcturus (29 Nov 2021)

Thank you for the replies. This system will be installed on an old building with 5 apartments and the majority agreed on the system - I was the only one against. It is installed on the main water pipe coming into the building, well before the pipe routing into the apartments. The technical installation is already concluded and it will be put online shortly. Currently there is no plan for a bypass. What I do know is that the system is somehow certified by the public health authorities and that such system is rather common around here in Germany. 

So, I think I need to start looking for a RO system... the issue is going to be storage tank.


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## Djoko Sauza (29 Nov 2021)

Could you not run the RO hose straight into the tank?


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## MichaelJ (29 Nov 2021)

Hi @arcturus  I assume your living in a condominium or apartment building of sorts... If this is a resin based water softener, could you possibly ask the management to use Potassium Chloride (KCl) instead of Sodium Chloride ?  Its more expensive, but might not be that big of a deal. Aside from the aquarium, the elevated sodium levels can be a human health concern as well - especially for people suffering from hypertension, diabetes etc.

I've been using KCl for a long time now. The tap water comes out at "0" GH. And I mix it with RO water and remineralize. Of course the Potassium level is very high, so I don't have to worry about dosing any potassium.

You don't want to pummel your tank with Sodium for sure, so the only viable way to get rid of the Sodium is run the tap water through an RO unit.  Since you need 100 L/weekly it might be problematic if you dont have space for a storage tank, so you might have to lower the WC or split it into two weekly WC's... whatever is practical. How big is your tank?

Cheers,
Michael


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## arcturus (29 Nov 2021)

MichaelJ said:


> Hi @arcturus  I assume your living in a condominium or apartment building of sorts... If this is a resin based water softener, could you possibly ask the management to use Potassium Chloride (KCl) instead of Sodium Chloride ?  Its more expensive, but might not be that big of a deal. Aside from the aquarium, the elevated sodium levels are can be a human health concern as well - especially for people suffering from hypertension, diabetes etc.


Yes, I live in an (old) apartment building with 5 five apartments. The filter is installed in the basement in the main water pipe. A bypass is not feasible without significant workarounds since the routing to the apartments is on the ground floor and not in the basement. 

The Sodium Chloride filters are rather standard around here. I will ask about the KCl salts. Thanks for input!



MichaelJ said:


> I've been using KCl for a long time now. The tap water comes out at "0" GH. And I mix it with RO water and remineralize. Of course the Potassium level is very high, so I don't have to worry about dosing any potassium.
> 
> You don't want to pummel your tank with Sodium for sure, so the only viable way to get rid of the Sodium is run the tap water through an RO unit.  Since you need 100 L/weekly it might be problematic if you dont have space for a storage tank, so you might have to lower the WC or split it into two weekly WC's... whatever is practical. How big is your tank?


The tank is a 120P, ~270 liters total volume. It has ~200 liters of water after discounting substrate and hardscape. I am exchanging 40-50% every week.

By the way, would the output pressure of an RO system be sufficient to push the filtered water up to a height of ~2 meters? If so, I think I have found a place for a RO water tank


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## arcturus (29 Nov 2021)

Djoko Sauza said:


> Could you not run the RO hose straight into the tank?


Theoretically yes, in practice no. RO filters have a very low flow rate, unless you get an industrial-grade filter. It would take many hours to fill in the tank. Add to that the water temperature difference (temperature of tap water is now ~12C and tops at ~15C during Summer), plus the need to add the salts to re-mineralize the RO during the fill process.


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## MichaelJ (29 Nov 2021)

arcturus said:


> By the way, would the output pressure of an RO system be sufficient to push the filtered water up to a height of ~2 meters? If so, I think I have found a place for a RO water tank


For what its worth, I just tried with my RO system and the result was negative. When I raise the outlet hose up to about 1 meter above the RO outlet the output slowed down considerably... at 2 meter it was a down to a drip. It  also depend on the water pressure and the inlet length of the output hose  (the pressure on the tap my RO unit is attached to is around 45-50 PSI / 3.25 bar).

Cheers,
Michael


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## Angus (29 Nov 2021)

MichaelJ said:


> For what its worth, I just tried with my RO system and the result was negative. When I raise the outlet hose up to about 1 meter above the RO outlet the output slowed down considerably... at 2 meter it was a down to a drip. It  also depend on the water pressure on the inlet length of the output hose  (the pressure on the tap my RO unit is attached to is around 45-50 PSI / 3.25 bar).
> 
> Cheers,
> Michael


Could always use a booster pump before the RO unit to up tap pressure and reach appropriate head height.

mine doesn't like being over 1 meter above the RO either, seems i'm on a similar pressure to you michael.


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## MichaelJ (29 Nov 2021)

Angus said:


> Could always use a booster pump before the RO unit to up tap pressure and reach appropriate head height.


Sure thing and a good idea!


Angus said:


> mine doesn't like being over 1 meter above the RO either, seems i'm on a similar pressure to you michael.


Sounds like it, yes.

Cheers,
Michael


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## ian_m (30 Nov 2021)

Something like this would be suitable, obviously much much smaller would be OK in domestic setting. Has an 8bar pump, so RO membranes are running at their rated pressure, stop/start control so when storage container is full it stops pumping and a Chloramine/Chlorine pre-filter so you don't destroy your RO membranes.

RO-Man.com | Reverse Osmosis and Water Filtration Systems

You can obviously assemble all the bits for yourself. To keep the cost under control.

People have built there own systems, pump, valves, RO units and storage containers, no issue.


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## Aqua sobriquet (30 Nov 2021)

I was under the impression that here in the UK the installer was obliged to provide a direct water pipe for drinking and cooking purposes? I guess I was wrong. Perhaps it should be a legal requirement? Obviously Germany have their own rules but forcing residents to use only artificially softened water sounds wrong to me. I’d certainly be going over to bottled water for drinking.

It surprises me they are still being installed.


			https://www.lifesourcewater.com/blog/water-softeners-banned-by-law.php


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## dw1305 (30 Nov 2021)

Hi all,


Aqua sobriquet said:


> I’d certainly be going over to bottled water for drinking.


I've <"never drunk bottled water">, but if the only other alternative was to drink sodium softened water? I would drink bottled, not only for <"health reasons">, but because softened water tastes vile.

cheers Darrel


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## ian_m (30 Nov 2021)

dw1305 said:


> Hi all,
> 
> I've <"never drunk bottled water">, but if the only other alternative was to drink sodium softened water? I would drink bottled, not only for <"health reasons">, but because softened water tastes vile.
> 
> cheers Darrel


My Dad used to work in the bottled water industry, solving "issues" (generally bacteria and uranium salts !!), but would only ever drink tap water as it had chlorine in it, unlike bottled water !!!


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## dw1305 (30 Nov 2021)

Hi all,


ian_m said:


> but would only ever drink tap water as it had chlorine in it, unlike bottled water !!!


I really don't understand bottled water. Personally I have fantastic water <"out of the tap">, why would I want to pay more for an (often) <"inferior"> and much less environmentally friendly product?

In the UK you could legally <"bottle your tap water"> and it would pass all the regulatory standards, the only thing you aren't allowed to do is describe it as "_Natural Mineral_" or "_Spring_" water.

cheers Darrel


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## Nick potts (30 Nov 2021)

dw1305 said:


> Hi all,
> 
> In the UK you could legally <"bottle your tap water"> and it would pass all the regulatory standards, the only thing you aren't allowed to do is describe it as "_Natural Mineral_" or "_Spring_" water.



Reminds me of an only fools and horses episode lol

I have never drunk bottled water either and have never understood those who refuse to drink tap, simply because it's tap.


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## Aqua sobriquet (30 Nov 2021)

I’ve heard Tap water quality in parts of the USA is dreadful. Whether it’s actually bad for your health or just makes you want to be sick is another matter!  Weren’t some folks able to set light to the tap in fracking areas? !


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## arcturus (30 Nov 2021)

Aqua sobriquet said:


> I was under the impression that here in the UK the installer was obliged to provide a direct water pipe for drinking and cooking purposes? I guess I was wrong. Perhaps it should be a legal requirement? Obviously Germany have their own rules but forcing residents to use only artificially softened water sounds wrong to me. I’d certainly be going over to bottled water for drinking.



There are strict federal regulations regarding water quality in Germany. Residential water filtration systems must be certified and calibrated so that the filtered water complies with the parameters defined in the regulations. Sodium (Na) is limited to 200 mg/l, which I believe is the same limit defined in UK's Drinking Water Directive. However, and according to the latest 2020 water report, the concentration of Sodium in the water provided to my place was between 19,9 and 22,9 mg/l, which is just ~10% of the limit.


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## dw1305 (30 Nov 2021)

Hi all,


Aqua sobriquet said:


> I’ve heard Tap water quality in parts of the USA is dreadful. Whether it’s actually bad for your health or just makes you want to be sick is another matter!  Weren’t some folks able to set light to the tap in fracking areas? !


Unfortunately "market forces" at play in a, basically unregulated, environment. It is much more "cost effective" to add a lot of chlorine to the water supply <"than actually treat it">.


> ......_Five minutes later I realize I did not add Prime to the 20 long. Too late, all six fish are dead. Anyone that has attended CatCon knows how deadly the water is here. No fish can survive in untreated DC water for more than a minute or two_...........


It is the <"same with power outages">, horrible and unusual for us, but really common in the USA. If you go onto <"PlanetCatfish"> there are multiple threads of woe from the USA.

cheers Darrel


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## dw1305 (30 Nov 2021)

Hi all,


arcturus said:


> Sodium (Na) is limited to 200 mg/l, which I believe is the same limit defined in UK's Drinking Water Directive.


It is the same. If you have more than about ~18 dGH in your incoming tap water, once it has been through the ion exchange unit, the treated water it will be over the 200 mg/L Na limit.

<"Companies that sell these units"> know that the calcium carbonate ~ CO2 equilibrium will not produce water with more than 18 dGH, unless there is another source of calcium (from <"evaporite minerals">) etc.  And if you have harder water than that? They can just <"sell you another filter"> to reduce the sodium levels.

A cynic might suggest that the 200 ppm limit and calcium carbonate solubility values are not unrelated, although the link between sodium and hypertension is not as clear cut as was once thought.

Because our processed food is awash with salt (and sugar) companies that sell water softening units can point out that drinking water is a relatively smaller contributor to our <"overall sodium intake">.

cheers Darrel


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## arcturus (1 Dec 2021)

Another question from someone that never used RO water in an aquarium... should I add water conditioner to the RO water before re-mineralizing it? I ask this mainly because of chlorine and chloramine (or byproducts of chloramine such as ammonia). Or will the water conditioner do more harm than good when used in the highly demineralized RO water? 

And do you have any suggestions for salts to re-mineralize RO water? The prices I have seen so far are outrageous...


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## sparkyweasel (1 Dec 2021)

Most RO units have a dechlorinating stage (such as an activated carbon prefilter) mainly to prolong the life of the RO membrane as chlorine can damage it.


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## bazz (1 Dec 2021)

Hi,


arcturus said:


> And do you have any suggestions for salts to re-mineralize RO water? The prices I have seen so far are outrageous...


I remineralise 140l of water/week with 4g-CaNO3, 10g-MgSO4, 5g-CaCl, 5g, CaSO4 and 3.5g-KCO3 which = dGH5.24 + dKH1.1.
Each chemical is around £10.00/kg, so for £50.00 I have enough chemicals to last me approx 4 years, according to my dodgy mathematics that's 25p/week.
Twice as much MgSO4 is used but this is less than half the price.
You can also remove CaNO3 and CaSO4 from the equation but it will increase the amount of Chloride and I already had these remaining from other projects.
So you could actually get away with spending £25.00 but this will obviously last half the time.
Cheers!


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## ian_m (1 Dec 2021)

arcturus said:


> should I add water conditioner to the RO water before re-mineralizing it?


Some people always add water conditioner to their RO water in case there is chlorine (from chlorinated water) and/or ammonia (from chloramine) getting through into the output due to worn out/failed RO elements. Also the RO water is probably one case where a chlorine and/or ammonia test kit would give meaningful results, as there are no other interfering ions/salts present in the water.

I learnt about this "issue" with RO water when going to a local fish shop when they had an open evening, where as well as trying to sell you stuff also showed what equipment they have for their tanks, how it works and how they verify it is working. 

They stored RO water in tanks from their pumped (8 bar) RO unit. RO unit had flow meters, measuring pre-filter (chlorine removal) flow as well as output flow so they knew when to replace the filter/RO elements. Might have been a dual stage/element RO unit to reduce water wastage, as they were on a commercial water meter. They also tested their RO water for chlorine & ammonia before selling to the public and cutting with tap water to use in their display tanks.


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## Aqua sobriquet (11 Dec 2021)

It seems extremely difficult to find unbiased opinion on the health effects of using artificially softened water. 99% of the “information” seems to come from companies that manufacturer, supply and fit water softeners. Not surprisingly they say it’s perfectly safe! I therefore though It quite amusing to see another biased report that stated the opposite! Not surprising as they make water filters. I wonder though if there’s any truth about damage to water pipes etc? 









						What is Soft Water and Why You Should NEVER Drink it!
					

What is soft water, why you should NEVER ever drink it and what types of safer water should you drink instead?




					www.mrwatergeek.com


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