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Water Softeners & Whole House Filtration

Discussion about fish health and water chemistry.

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Post Tue Feb 06, 2018 2:29 pm
jschlosser Level 1 Member
Level 1 Member

Posts: 2
We are building a house where the city water is 25dH or thereabouts and pretty nasty tasting. We will be adding a whole house filter to deal with the funkiness and need to soften the water as well. I am looking at these "salt-free" conditioners instead of a salt-based softener. The sales guy at Pelican says he has been keeping tetras in water using their product. But he's a salesman. Does anyone have any experience with these?

I only keep fish that can live in the water I have, so extra stuff like RO, no carting it in from some body of water, etc. My fish have to live in the water I have. I am in a position right now to control the water that comes out of our pipes so I want to get this right for me and my fish.


JoAnn Schlosser

"All men are equal before fish."
-Herbert Hoover

Passionfish Level 20 Member
Level 20 Member

Posts: 12302
Location: apple valley, mn
Hi JoAnn,

Salt-free systems do not remove calcium and magnesium from the water and therefore do not "soften" the water. If water is 25 degrees permanent hardness before salt-free treatment, it will be 25 degrees post salt-free treatment. A salt-free system is a water conditioner is not a water softener.

Hard water is mostly calcium carbonate with significantly less magnesium carbonate. Calcium and magnesium are cations and carbonate is an anion. Calcium carbonate crystals may exist in various morphic forms; which are calcite, aragonite, and vaterite. Each of these polymorphs forms a different crystal structure resulting in different solubilities in water.

A salt-free water conditioner most often uses ceramic media that attracts dissolved calcium and magnesium ions to form aragonite crystals. Small aragonite crystals are then released from the ceramic column and remain in the conditioned water as a crystal. If calcite crystals form, these crystals tend to dissociate into free calcium cations and free carbonate anions. To recap: Feed water contains dissolved calcium carbonate, the water passes through non-salt water treatment resulting in the formation of aragonite crystals. Aragonite crystals are very small but do not dissociate into free calcium and carbonate.

What is the advantage of salt-free water conditioning? The only advantage is reduced limescale in hot water pipes and hot water heaters. In addition, as the water temperature is raised, aragonite crystals become more soluble and dissociate into free calcium and carbonate.
Whereas soft water advantages are easier cleaning with soaps which includes bathing, clothing, dishes, etc. Also, lime scale cannot form in hot water pipes or hot water heater because there is no calcium in soft water. But wait there is more.

A whole house water filtration system is most often a high capacity reverse osmosis system (RO). However, the term could also be used for filters to remove particulates, chlorine, and volatile organic compounds, without an RO membrane filter. Using salt-free treated water as feed water to an RO system is a mistake IMO. The useful life of RO membrane would be significantly shorter with aragonite in feed water than the use of soft water as feed water to RO unit. It is true that a particulate filter needs to be in place to protect RO membrane but I doubt the particulate filter would remove aragonite and if aragonite dissolves into ions, the RO membrane life will be considerably shorter.

RO water is a great source water for creating soft acidic water for tropical fish. However, we do not need to keep fish requiring soft acidic water, we can keep fish that live well in hard, alkaline water. Often fish that breed in soft, acidic water live well in hard, alkaline water but they cannot breed in hard water. Therefore, these fish can be kept for enjoyment. RO or no RO is based on what you want to do with your fish.

A presumption is Loretto supplies well water from aquifers to residents. I would go with a real water softener that uses salt. If you want to set up RO later, you will have correct feed water. Also, soft water has other advantages already discussed. Whole house system will need a particulate filter, then a charcoal filter at a minimum. Charcoal will remove volatile organics that cause odors. These filters will produce water with pH of about 8 as carbonate will be in the water. Calcium and magnesium will be zero or close to it. For fish that need some calcium present in water, use limestone in tank filter and/or decorate your tanks with limestone rocks, substrate, etc.

Well water with high iron concentration will require a separate filter to remove the iron. When iron levels are high, the water is not clear, smells foul and is likely unhealthy to water drinkers and fish.
Like a complete unknown

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