Q&A: Iron in Pool Water and Chemicals to Remove Iron

Question: Hi, I just ordered the Ferri-Iron Tabs after doing a web search for Iron removal and I have a few questions about it, I’m hoping these will save our pool! 

Here’s the background: We purchased our home in January with an existing 20,000 gal in-ground vinyl lined pool with a salt system.  We have had issues since opening with green tinted water and light brown stains on the floor walls and stairs.  We did the “vitamin C” test after someone recommended it to us and decided it was probably an iron issue.  The first time we treated we used a container of Metal-Free but that seemed to do nothing.  A friend gave us some Jacks Magic Magenta Stuff to try, and within a few hours the water really looked great though there were still some staining but it was acceptable, I thought our problems had been solved!  We added a few ounces of Magenta Stuff each week and the pool really looked nice, but gradually the brown stains began to come back.  My wife spoke with the local pool supply chain and they sold us more metal-free and some stain remover.  They instructed us to drop the chlorine level, add the stain remover, then the metal-free, then after 24 hours clean the filter (cartridge) and bring the chlorine levels up with liquid Chlorine.  Within a few hours the pool was neon green, worse than before we started. Frustrated we decided to let a few days go by, and the pool actually started looking a little better, but still green/brown.  We gave Jacks Magic a call and explained our situation.  They recommended a similar process using their products and adding a filter powder which worked great until we brought the chlorine levels up.  This time we raised the levels gradually over a week period using only the generator, but the green water and brown stains came back.  Now our water is more tea brown than green and we were ready to just fill the pool in and give up, until we came across the Ferri-Iron tabs online.  I should mention we have had good levels of Ph, Alkalinity, etc.

 So I ordered the tabs and a container of Stain-Free, they should be here Wednesday but I do have a few questions!  First, how do these differ from what we have been doing?  Should we try them out without doing the Stain-Free first, just to see if they actually help, or go right intot he stain removal first?  Does the Stain-Free require the chlorine levels to drop?  Would the tabs benefit from adding any powder to the filter first?

Any other recommendations?

Sorry for the long message but I thought I should explain the process we have been going through! Thanks for your time and comments!

Response from the Pool Guy Team:

Here are some thoughts based on your questions.

I have used StainFree successfully without doing anything to “prep” the water. That being said, following label directions are always helpful.

Sequestering the Iron

To remove the color from your pool, you do need to get the iron off the pool surfaces first and put it back into solution (get it to dissolve back into your water), which you can do with the Stain Free. Once the iron is back in the water, then you have to sequester and remove it(get it to leave solution and be trapped by the filter). Once you get it to do that, you should only need to treat the water with ferritabs after you add new source water if it is high in iron.

Cartridge Filters and Iron Removal

With a cartridge filter you will see the filter clog up quickly with the iron sediment when the process works correctly. FerriTabs work best with a sand filter, and we have used them with Cartridge filters, it just takes a little more work. The beauty of a sand filter is that you can backwash the iron out of the filter without needing to do more. With a cartridge filter you will need to take the filter out, hose it down, and maybe even clean it with a filter cleaning aid. What we have done with pools with cartridge filters is do the process to remove the iron, give it about 24-48 hours to work, and put in a brand new clean filter, while taking the other out for cleaning. Then you can clean that filter and get it ready to go back in, and the next time  you treat or the filter gets clogged you can swap them out. You can also just clean the 1st filter and put it back in – resulting in a bit of downtime for your pool. If your cartridge hasn’t been changed in recent times, I’d also explore if it’s time to replace it anyway.

High Metal Content = Green Water

When a pool has a high metal content, the pool can be green. A pool can also turn green when the pH goes high, which sometimes happens with the addition of liquid chlorine because of it’s high pH level (between 10-13 in many cases). High pH can also cause metals in the water (copper and iron) to turn green and brown when they are suspended in the water.

I have not heard of the best results using Metal Free for high iron content pools, though we do like Jack’s Magic products in general.  The Magenta Stuff is meant to prevent stain and scale on the surfaces of the pool vs. take anything out of the pool water, so it makes sense that it didn’t solve your issue.

 Treatment with FerriTabs

What I would recommend for your pool, especially if the water is so discolored, is to treat with a few of theFerriTabs first (based on how large your pool is). Then let the filter work and see if the color changes. Once we know that the FerriTabs have been working it would make sense to use the stain free next, followed by another treatment of FerriTabs.

Always keep these answers handy when having your pool issue diagnosed:

  1. How many gallons is your pool?
  2. What is the surface, vinyl, gunite or fiberglass?
  3. How many hours a day to you run your filter?
  4.  What are your current levels of:
  5. Chlorine
  6. Alkalinity
  7. pH
  8. Calcium Hardness
  9. Stabilizer