Epsom Salt

ejpool

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Apr 2, 2017
1
WA
So I read one old thread here that implied that using epsom salt at 1 lb./ 50 gallons wouldn't be a problem for corrosion. Would it also help minimize bacterial growth?

I want to minimize chlorine, or not use it at all, in my new (used, probably 10yo) softub 140. I ordered the nature2, and got some MPS (the softub site says not to use it, and it voids the warranty, but another site that sells softubs says it's okay to use in small quantities). I also have a filter sock, which i intend to wash weekly.

So is there a level of epsom salt that WOULD help prevent bacteria, and WOULDN'T cause corrosion (or at least not too quickly)? I'm in western WA, and my water is very soft, so scale isn't otherwise much of a concern.

Thanks!
 

pooldv

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Aug 10, 2012
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Welcome to TFP!

What does the nature2 use to kill bacteria? I don't think it has anything in it that kills bacteria. It probably states in the Nature2 literature that chlorine use is required for a properly sanitized tub. Most non-chlorine sanitizers are required by federal law to state that chlorine is also required. Since you have to use Chlorine you might as well skip the extra expense of the Nature2. I've been using this process in my tub for quite a few up years now and it is great, How do I use Chlorine in my Spa (or pool)?

I am not aware that Epsom salt has any bacteria killing properties. We have used Epsom salt in our tub since we got it. I don't know how much, we just put some in occasionally.
 

JoyfulNoise

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May 23, 2015
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Tucson, AZ
Epsom salt is simply magnesium sulfate. It has no antibacterial activity whatsoever. Adding it will not allow you to reduce your sanitizer levels in anyway. Sulfates can lead to faster heater corrosion if the heater is made out of Incoloy instead of titanium.

If the Nature2 system is silver ion + MPS, then that is an approved hot tub sanitizer but only when the tub temperature is kept above 96F (100F is better). Do note that silver/MPS systems typically are more expensive than chlorine and usually require more frequent water exchanges.

If this is a used tub, TFP suggests you use Ahh-some to purge it before setting it up for use.


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AUSpool

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I agree, Epsom salt has no antibacterial effect. No antialgal or antifungal effect either. I think it is more likely to promote growth then prevent it but that would be a bit organism specific. I recall magnesium being used in marine aquaria at very high levels (~1500ppm) to discourage algae growth but I don't believe there was any real evidence it had any affect.
 

JoyfulNoise

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May 23, 2015
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Magnesium is more likely to act as a nutrient than a sanitizer. All plant life (algae and certain cyanobacteria included) need magnesium as a growth nutrient because chlorophyll(s), ie, the cellular pigment responsible for all photosynthesis, requires a magnesium ion (Mg2+) at the core of the chlorin-complex. Nature, being beautiful by design, has a similar structure in mammalian biology called hemoglobin where the porphyrin ring (aka, heme) contains the ferrous ion (Fe2+) at the center. Of course, anyone who has ever grown tomato plants knows all this from direct experience - when a tomato plant starts to get a little yellow from growth chlorosis, you spray the plant with a mixture of epsom salt in water (about 1 tablesspoon per gallon) all over the leaves. The next day the plant will be green again. Here in Arizona, I have to feed my citrus both small amounts of magnesium as well as highly chelated iron to ensure that they don't get chlorosis from the high pH, calcium rich soil we have...
 

AUSpool

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... I recall magnesium being used in marine aquaria at very high levels (~1500ppm) to discourage algae growth but I don't believe there was any real evidence it had any affect.
I should clarify this. Thinking more about this, magnesium was used at high levels in aquaria as a nutrient and not as an algaeside. It was used to encourage beneficial algae at the expense of the nusience algae but given the long term nature of application there is no way to know if the change in magnesium concentration had any real benefit.

Edit: Just to add a little more, magnesium is a listed in my old microbiology text book as a macronutrient for all microorganisms, it is found in many enzymes and stabilises ribosomes, nucleic acids and cell membrains.
 

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