Metals/Algea/cya

[Traveler]

Hi I'm new to the forum and pool ownership so please bare with me as I have so many questions and not sure how to post them. But here goes.
First- is what should be the correct level of CYA for my SWG pool. My Hayward T-3 manual says 30-50ppm, online web references anything higher that 50 is a waste of money as CYA as its has beminishing returns above 50. My local PAP store says no less than 90 and here on this site, I'm reading 70 to 80ppm. So using my Taylor K-2006 gives me a 70ppm reading, but what number should I be shooting for.

Second- I've noticed a brown staining on plastic drain covers and jets as well as a blotchy spots in the shallow end of pool and steps. so I applied Vit C in sock on them and stains immediately disappeared, leading me to believe I had iron staining. (water analysis showed 0ppm Iron). I purchased and followed a CU-later program using both absorbic and citrus acid, a sequestering agent and their proprietary polymer to collect the sequestered metals in a sack placed in the pump strainer basket. The Culator Kit was good for 20k gal pool so I used half in first application and so results. The Mfg. wants you to maintain chlorine at <1ppm for three weeks after treatment which was impossible in my 5K gal pool so it ended up plating back out to pool surfaces after a month or so. My second attempt may be successful as I maintained <1ppm for three weeks and then remove the polymer sacks and hopefully the iron with it. But now I have the early signs of green algae growth in corners and slow moving water areas due to the low chlorine levels during CuLator treatment even though I was using a linear a polyquat algeacide and Chl use is in high demand from my SWG, which can't keep up with demand. The water after extreme brushing and vacuuming is hazy, but not green.
So today per this site's recommendations I'm on day one of a slam using 1lb of Cal-Hypo and looking for any recommendation going forward.

I know now this is a book info requests, but wasn't sure so I spilled my guts......help me out please.

 

[Analogbytes]

Welcome to TFP, the best place to spill your guts. I will let someone else walk you through the chemistry of why we recommend you CYA with a SWG to be 70-80.

I do want to point out that we recommend you SLAM with liquid chlorine or bleach, not Cal-Hypo as that adds CH. if you need to add, CH, that is fine. Can you post a full set of test results from your Taylor kit? Great kit, by the way!

 

[Swampwoman]

Hello and welcome, Traveller. I'll try to break down your areas of concern:

Re:CYA
My own preference is to maintain my SWG at a CYA of between 70-80 per TFP reccs, according to this guideline: [fc/cya][/FC/cya]
I trust the science that underpins the TFP recc.

Re:Staining
I also manage iron in my pool because I am on well. There s a high likelihood your stains were iron, unless you used any products with copper in them or have copper parts corroding.

I have not found Culator useful and frankly would not put much stock in its efficacy as, as you've likely by now determined, even if it did work, is not worth riding FC below recc levels.

Going Forward on Slam And Staining:

Since you've started the SLAM (liquid chlorine is preferred as suggested unless you NEED more calcium) you now want to follow direction to complete per SLAM Process.

Once you are complete, you will quite likely need to add a new startup dose of sequestrant because the SLAM may have worn it down.

With swg, the iron could be from source water (slow build up), trace amounts accumulated in salt addition (nearly all have a little), blown in stuff such as fertilizer (contains iron) or possible corrosion of steel pool parts, eg bolts, ladders, etc.

If your source water is not well water with high iron, and/or if your city water reports low iron levels, it is aways better to dilute built up iron concentration with a partial water change when possible.

However, if you're on well with iron, filtering va home water softener or mechanical filters like the Pentax 10" with a 25:1 reducing filter attached to your outdoor spigot in my experience helps control the iron concentration to manageable levels.

So, for the moment, Slam, then Sequester, and as you are able, dx the source of metal...if sequestrant wears off super fast (you will need to maintain it every few weeks) its a sign of higher concentration which may ave you investigate further at your leisure and consider dilution and prevention methods.