Brown Slime in Micro Filter & Yellow Stinky Water

by Simone
(New Zealand )

Our Spa pool was new three months ago, it came with two filters and one micro filter. We used "simply silver" as our sanitiser.

Slowly the water turned yellow and started smelling like a bad tadpole tank. We noticed the micro filter (which is not to be cleaned, only normal filters get cleaned) had brown slime around it. Five days ago after clearing out excess dirt etc...

We removed the simply silver and immediately added our lithium sanitizer (70% lithium hypochlorite) 3 to 4 teaspoons a day to raise the chlorine level (running filtration 10 hours per day) cleaning the two filters each day, the chlorine reading is 20 but the water is still yellow (it never went cloudy or whitish) we were under the impression that this should be starting to clear - what are we missing?

Is there anything else we can do.

Thanks for the question Simone

I'd like to have your complete chemical readings, the actual numbers:

Chlorine, CYA (cyanuric acid/stabilizer), pH, Alkalinity, Calcium Hardness, and Metals (iron and copper) and names of any algaecides you may have used along with clarifiers, phosphate removers, and/or flocs. It makes troubleshooting much easier.

Next is the use of lithium hypo. In effect, it's the same as pool chlorine just at a higher price. You'd be better off using regular chlorine or grocery store bleach. Just double the amount of the bleach.

I'm not too familiar with "simply silver" but could that be a copper silver ionizer? If it is you may be putting too much copper into the water. This can cause stains and unbalanced water.

Normally an ionizer and Ozone are a waste of money. You'll always hear about this and that product that's better than chlorine or bromine. Nothing is further from the truth.

If you're shocking the hot tub you need to do it all at once, not over a period of time. Shocking is a process, not an event. The trick is to get AND keep the chlorine above 10 - 12ppm for a period of time. You'll need to manually dose the spa with with chlorine.

It sounds like the chemical numbers are off. Give them to me and we can go from there.

I hope this has answered your question to your satisfaction.

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Thank you.

Hope this helps.


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Mar 22, 2014
Thank you for your response
by: Simone

So readings today are much less than when I wrote my original query... (It has been a couple of days and we have layed off on the chemicals) water smells clean, no slime but still yellowish... So originally we has the FCI (free chlorine) at 10 (we read it wrong as this bromide which would have been 20) anyhow today it is at FCI 3 / ALK 120 / pH7.8 / TH 250

The key ingredient in simplesilver, is silver oxide, but they don't say much more than that - They do say you can use chlorine with it (but not bromide) not sure about copper - although gut feel is that your comments feels right and I believe most silver is produced as a byproduct of copper.

So outcome we are going to be using Chlorine as we think the Simplesilver just can't cope with our three boys (ages 4,7 and 9) who run across the lawn jump on trampoline and then go back in spa - they are grubby little boys and we think Clorine is possibly best fit for this use.

Thank you for your advice and I love your site :-)

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