Side stream metal removal filter Experiment

[basod]

Preface of this test:
My well doesn't have high iron, but I have copper piping in the house. Previous owners used copper based algaecide and I've always had yellowish stains on the sloping surface of the deep end with some darker stains on the vertical sidewalls. I did a direct ascorbic acid treatment 2 weeks ago with no sequestrant, it removed the vast majority of unsightly stains, so I don't always think there's a bloom a coming.

I know there is a bit of "hive mentality" here in that the only way to remove metals is through a drain&refill with metal free water. I've used this similar setup in many industrial applications for reduction of free metal ions (on a larger scale) with success so why not try it on the pool.

Two Dupont filter housings plumbed post sand filter. First has a 5micron filter, second a charcoal filter. Timed bucket test ~5gpm on new filters with backpressure from the eyeballs.
I added an extra valve off the Tee on the left for a future fill hose connection.
Eliminated any copper end hose connections as I noted some copper precipitate inside the existing fill hose.

Simple DIY project, total cost of materials ~$125, including an extra set of filters. Filter housings can be sourced for cheaper money online, these were $33/each at walmart(with tax)

Note how much metal scale was found in the 2" section cut for the 1.5" tee

 

[cowboycasey]

I love it, did it cut the copper down, do you think it would work for iron also?

could you link to what you used, I think it would help others if they tried this

 

[basod]

Apologies the second internal pipe photo won't load reached my limit on helping folks on a "free website"
i have separate iron removal tower running now. I'll post some PDFs of design as I don't plan needing one myself

 

[basod]

Appears to be removing something after 1week 2-3hrs operation daily the inside of both filters are turning light brown

 

[basod]

Also experimenting with a better AA direct treatment.
I found that soaking rags in dissolved AA letting them dry then using them to wipe areas of stained surfaces the metals stay on the towels. Instead of continually dissolving the metals from the wiping towel which is what happens using a sock full of vitamin C pills.
The towels can be cleaned in a mild MA solution bucket dispose of this water rinse rags and soak & dry towels in original AA solution.

 

[Swampwoman]

Basod, can you describe where in the plumbing you're adding the filtration units?
Also, won't the charcoal remove the chlorine?

We're you concerned that a 1 micron after the 5 micron would slow flow too much?

For fun, I'm going to test a 1 micron on raw well when I recuperate a bit more and see if I can get a sense of reduction from 2 ppm iron.

 

[zea3]

You can use a free photo hosting site like photobucket to post pictures on TFP.

 

[duraleigh]

So, to make this system work, you must first precipitate the metals in the water, is that correct?

 

[basod]

The filters are plumbed into the discharge from the sand filter using a 1.5" slip tee and 3/4" slip reducer.

Right now I'm not using anything to precipitate the metals just series filtering to prevent the finer micron from plugging up to quickly. I may add a third housing and use the supplied 30micron elements in it.
The flow of 5gpm has dropped less than ~ .1gpm since install.
I've tested pool water FC and FC from the return hose with no indication of FC reduction.

Something I noticed yesterday the 5micron had a small amount of debris in it, assumed possible channeling in the sand filter and while I had it apart for a deep clean the discharge piping from the filter was extremely dark red/brown similar to the section I cut out. The suction piping had minimal light brown staining.

Last year when I tried the first deep cleaning and abandoned after the sand was just full of debris, I changed the sand out and found a rusted 3.5" 16penny ringshank nail resting on one of the laterals. It probably was dropped in during filter maintenance as I have to remove a set of stair treads over the filter housing to access the multiport valve.

My fear is there is a bunch of iron deposited on the return piping(well I know there is) and doing any future AA treatment will dislodge more iron into the water.

 

[basod]

So, to make this system work, you must first precipitate the metals in the water, is that correct?

For folks with high iron content it would definitely improve the effectiveness of the filtration.

Whole home iron filtration uses either air injected through a venturi or pump, and uses the oxygen to oxidize the iron into larger particles inside a vertical cylinder that can be filtered out after time contact in the tank.

I was going to build a 4" tower out of PVC with a venturi and plumb it upstream of the filters, and I may still do that for the sake of experimenting.
In lieu of air induction for an oxidizer, bleach could be used at a much more affective metered rate. That's why we see all these AG Intex pools turning brown when filled from high iron wells and shock is added - the iron is oxidized.
If the tower works the secondary fill connection could be used to prevent the metal from getting in the pool to begin with.

 

[basod]

Just became a TFP supporter to drop some more pictures - didn't realize it was tax deductible.
have to wait for admin to increase my file sharing size

 

[cowboycasey]

Awesome, thanks for donating, yep, all tax deductable

 

[basod]

so here's the pic from my return line coated in assumed iron , exterior mess from when I oversprayed/stained the deck

 

[basod]

Spider gasket had completely failed so that's my cause of debris on the 5 micron filet element.
Restarting the control experiment tomorrow on new filter elements after silicon sets up.

Plan on acid washing used filter cartridges in diluted MA bath

 

[basod]

An update:
After changing spider gasket I let everything setup on Monday afternoon FC was 5. Tuesday morning was overcast and the entire pool surface was coated in dull yellow-green algae.
So I vacuumed/brushed backwashed and brought Fc up to 15 passed OCLT Tues night-wed morning. Yesterday morning algae was back with FC of 12, did a more thorough cleaning. Decided to pull main drain cover as it is plugged from a pipe leak ~8yrs ago. It was full of gross stuff.
Bottom of main drain lid looked dark brown/red like the inside pipe picture so it sat in an diluted MA bath while I scrubbed down everything else.
Put some DE on the sand filter and water started clearing up
Passed OCLT this morning @12FC, water has just a very slight cloudiness.

Didn't notice any terrible metal staining from either of my two SLAMs so a may have turned the corner on my metal problem.
This weekend I'm going to play around with the AA soaked towels some more to see if I did plate any metals out.

 

[basod]

Here's a few pictures of the filters. To ensure this isn't hocus pocus the 5micron has been being rinsed off in a bleach bucket every day/two it always turns the water red-brown but stays dark on the inside. The 1 micron filter never leaves any residue in a bucket but has turned dark brown internally.
Flow had reduced to 3.8 gpm in side stream mode, I never did any tests from my well fill for gpm but that would vary for everyone depending on well pressure and piping restrictions.

The left side of the 5mu filter is white from where I rubbed a small amount of dissolved AA to show it's metals both filters rinsed and soaked in high FC bucket prior to that test. Tried to wipe inside of 1mu filter but the material started to lift/disintegrate.
Originals and new filters side-by-side

 

[samt]

With your annual rainfall and your plumbing skills you could invent a rain collecting device either from your home rain gutters or something else and completely replace the water with iron in it with rain water that is iron free. I have been doing this the last 2 yrs and can really see a difference in my stains. Just by looking at where you live, your average rain fall is about 56" a year.

 

[basod]

With your annual rainfall and your plumbing skills you could invent a rain collecting device either from your home rain gutters or something else and completely replace the water with iron in it with rain water that is iron free. I have been doing this the last 2 yrs and can really see a difference in my stains. Just by looking at where you live, your average rain fall is about 56" a year.

that's a possible idea. Most of our wet season is when the pool is covered pump drained, and the amount of leaf & tree debris coming off the roof even if filtered would require some disinfectant prior to wanting to pipe it under the cover.
Most of my iron problem probably came from that nail that was in my sand filter and it is deposited on the inside of my PVC returns. I toyed with an acid wash of the return piping but run the risk of failing a glue joint(bigger problems then some stains). I may do something like that before a future liner replacement.

This will prevent any future fill iron plus a constant polishing if any iron comes into solution when pH goes low.

 

[basod]

So I built the time contact towers -and before anyone chimes in that DWV isn't pressure rated - send me a check for 4" schedule 40 + fittings, this system is under only back pressure from the filters.
My initial attempt at a simple 90deg venturi worked in testing(without backpressure from the filters) but failed miserably once installed in the system.

So back to the drawing board... I was pondering instead of constricting the pipe for a venturi, why not add an airfoil internally? Similar to Bernoulli's principle except somewhat reversed - then found a product that is patented in Europe for aerating fish ponds http://www.hendersons.co.uk/wms/airmaster_venturi.html so after brainstorming a bit I remembered some of the PVC trim board I had leftover from residing my house.
This test venturi works incredibly well when placed in front of a return jet. I decided to make a more permanent termination point with a 1/4" NPT quick hose coupler and that totally screwed up my initial test of just stick the 3/8" OD tubing directly into the PVC diamond...When they say engineers solve problems they often create problems to solve

 

[basod]

The above "airmaster" simulated venturi won't work once installed upstream of the contact towers - but I know what to build if I ever need to lower TA in a 1.5"size connected to a return jet.

This is a link to what my methodical madness derives from - see page 3 for a diagram, page 2 is a good starting point for anyone with high fill iron.
http://www.qualitywatertreatment.com/PDF/Terminator-Lit_rev3.pdf

I may just go ahead and buy their system designed venturi (Waterite W-988) as it should work against backpressure, most of my searches around the web have yielded fish pond guys with issues whenever backpressure is introduced downstream of homemade venturi's