Good morning, Fm. I was in the hospital yesterday unexpectedly and didn't see the thread, but I will be happy to give you my take on the best way forward here.
I am on well, so I know how that battle goes, and also now know quite a bit about resultant high phosphates and how to keep water perfectly clear despite it
You have a lot of moving parts here, so take your time reading and understanding before you begin remedy, please. I am posting a lot of info here and I don't expect you to absorb it in one take
But I need to post it sequentially in a single post so that you can get the big picture before moving forward as I may not be around a lot to post back, depending on hospital jazz
My method suggested here has a bit of "front end" investment in terms of time, learning curve, and strategy, but the payoff will be a pool that is EASY PEASY to manage long-term
For starters, just to refresh, start out reading
ABCs of Pool Water Chemistry -- wherever I link, its something I want you to read a few times
Now, About Phosphates On Well
First off, the simplified truth of it is that IF you follow TFP pool care parameters, where your CYA is at a basically fixed level (notably preferably NOT 90) and use liquid chlorine or bleach to target daily to the [fc/cya][/FC/cya] -- you WILL NOT have problems due to high phosphates.
In other words, in what TFP calls a properly sanitized pool, where the FC is 7.5% of the CYA, phosphates will never matter because algae will always be killed before it can feed on the nutrient.
My phosphates can only be read via dilution and a high limit reader -- unneccessary for average user, used only in my case to experiment, btw. This is due to a heavy reliance on HEDP type sequestrants -- over time, they all break down into orthophosphate.
SO, in your case, despite the well, the best move you can make is a partial drain to get your CYA to a lower level, eg 40 would be ideal. You want to do this so that you can start using TFP pool care method to have a sure fire way to avoid triggering algae when you have high phosphates -- because I am pretty sure that life without sequestrant would NOT be viable for you on a well
BUT before you do that, there is the complication of the well, which I will try to help address in my steps below.
Preparation To Adopt TFP, Then Slam
1. TESTING - If you don't already have one, first order a TFT100 or Taylor k2006 test kit specifically. You need this type of FAS/Dpd test kit to accurately read your OWN CYA and to be in a position when you ultimately
SLAM Process to accurately read your FC frequently. Well management also goes better when you can precisely dial in your parameters.
2. EXTRA SEQUESTRANT - Before you slam to get rid of visible algae, I am going to suggest that you make sure you have a start up dose of metal sequestrant on hand because slamming will wear it down. With metals, its best to avoid shocking generally by keeping the water bulletproof to begin with, because the high FC can cause your metals to oxidize and stain or tint your water.
BUT you now have visible algae, so you will need to slam, so there are some ways to control any fallout you have from that.
Metal Magic sequestrant in particular has worked well for me to both sequester the metal AND remove fresh iron stains from high ph etc. Here's a link to how to test its efficacy. In your case, I'd get some of this on hand, but your existing brand may also be fine -- I just don't know it.
http://www.proteampoolcare.com/images/uploads/MetalMagicSpongeTest.pdf
3. FILTERING YOUR FILL WATER - Before starting your water change, consider creating a single or dual pre-filter set up in order to reduce the amount of NEW metal (presumably iron) going INTO the pool.
This will only reduce it, not eliminate it, but will help you going forward needing less sequestrant and getting less staining.
If you buy 1 or 2 of these filter housings:
Pentek 150469 3/4 Scientific
And in a 2-filter set up, a 5 micron and 1 micron filter: example
One Big Blue Sediment Filter Housing 1 Micron - 4.5 - - Amazon.com
(Or just the 1 micron)
And attach that to your fill source you will be able to mechanically remove a good deal of the iron. The amount depend on how high the ppm of iron are in your well, and the flow rate. The dual 5 micron to 1 micron approach is better because that helps the 1 micron not clog. Your filling will be slower.
Note that trucking metal free water in is always an option for dilution, but you'd still wan to filter your top up water anyway.
4. WATER CHANGE - once you have the test kit (if you don't already) and some way to reduce the new metal (like the filter set up I mentioned - you could also use a cheaper, disposable filter like prefresh, which is rated for 8,000 gallons, but as its disposable, the filter housing is a better long term option) then do a partial water change -- or a series if needed due to your water table.
5. TEST FIRST - BEFORE SLAMMING & BEFORE SEQUESTRANT: in your shoes, while changing 50% of the water, I would add some liquid chlorine to keep the FC higher, eg. 8 ppm, but not yet at shock level IF your current water is not already green from algae. I'd do this in the hopes that the water change plus higher FC would help avoid a full slam.
Then I'd do an
Overnight Chlorine Loss Test to decide whether I still needed to slam - but only f there was no visible algae. Visible algae necessitates a slam.
6. IF YOU SLAM - wait until you're done and passed the OCLT before adding sequestrant. If you need to slam, read up, post back, etc. everyone will help you through. Here's the link again:
SLAM Process
7. IF YOU DON'T SLAM - add a startup dose of your sequestrant.
If your water tints or you get staining during the slam, I feel you'll be able to clean it up with the sequestrant, so don't panic
Once you've done these things, going forward, you pool care regime will be super simple and quick. You'll check you ph and FC daily, and by using liquid chlorine or bleach, will only likely eed to check cya etc. monthly. By dosing to the higher end of the FC for your CYA daily, algae will never again have a chance to feast on those delectable phosphates
This is all true whether you have high phosphates or not. It just becomes even more important to maintain to the TFP parameters when your waters a little more nutritious/delicious to algae
