My 30k gallon pebble-tec pool has nice clear water but I am constantly doing the dance between minimum FC levels, ph balance, and metal staining. I use Borates and the pH seems to hold steady at 7.6-7.7 (best I can tell - I find the Taylor color matching to be tricky, wish there was a better test). I add acid about once a week but it always seems to settle back to 7.6-7.7 after a day or so. It is currently very hot here in New England and my pool is in full sun. I am running my SWG at 90% and FC is holding at 4-4.5 with 0 combined (Taylor DPD kit). My CYA is around 60, so I need to maintain FC around 4, and I live in fear that it will drop below this and I will get algae. I have some light brown staining here and there that does not brush off, which I believe is Iron staining. I fear that more will come out if I turn up the SWG, because it will cause pH rise. Also, I'm not sure how much more capacity to generate FC the SWG has, it is at 90% already. So my question is... should I add some Polyquat 60 as an algae prevention insurance policy as we head into a heat wave this week? Any downside from a chemistry standpoint? I have read here that polyquat 60 can make the pH hard to measure because it interferes with the indicator... is this true? pH balance in my pool (SWG and constantly aerating spillway) seems to be really important or else I get metal stains and scale. I did use some Metal Magic early in the season, and I think it has helped prevent staining... but I likely need to re-dose and the bottle says you have to drop your Chlorine to under 3 to use it. I am afraid to do that with the current weather. My phosphates are sky high (like 4-6k according to pool store test, I don't have a Taylor kit for this), which I blame on the Metal Magic. But it seems like phosphate removers would defeat the purpose of having metal sequestrant in there. At the same time, I must keep the FC in range or I am a perfect host for algae. So... chem geeks... what do you suggest - add the polyquat? Add metal magic despite higher FC? Attempt phosphate removal (this will be a PAIN given how much sequestrant it will take)? Water is perfect right now... but I'm dancing the dance and it is giving me anxiety!!
polyquat as algae prevention?
- Thread starter LivinMyBestLife
- Start date
- Jun 22, 2014
- 47,954
- Pool Size
- 17888
- Surface
- Fiberglass
- Chlorine
- Salt Water Generator
- SWG Type
- CircuPool RJ-45 Plus
You said it perfectly right there. You're dancing around what appears to be an elevated iron content in your water. Whether it's from a well or your local water supply, it will continue to increase each season. A possible saving grace for you is winter prep, closing, and subsequent rain/snowfall unless you use a solid cover. I would recommend that you test the stained area with some Vitamin C tablets just to be sure the staining is indeed iron.
You mentioned several possible supplementary products/measures in an attempt to help prevent algae while keeping the FC as low as possible. It's your pool and you have the right to try any of those if you wish. But in general, short of exchanging iron-saturated water for fresh water, the ideal scenario would be to first prevent algae by maintaining an ideal balance of FC-to-CYA as noted on the FC/CYA Levels then use a sequestrant on a regular basis. You can use a Poly 60 product if you wish. Other than a Poly 60 product possibly adding slightly to some FC loss, I'm not aware of any long-term chemistry issues, but @Donldson could confirm for us. Keep in mind some of this is speculation as it's very difficult to know how this "metals dance" will go without knowing an exact iron level in the water.
So when I do the pool store test, Iron tests as zero and copper at 0.2. But the Vitamin C does work to remove stains, and they are brown (not green), hence my conclusion that it is Iron. I may need to invest in the Taylor metal test but it is $$$. I don't know where the Iron comes from; I am using a hose filter this year when I add (municipal) water to the pool and that seems to help. There is a natural stone raised wall in the pool and I wonder if the rocks are actually the metal source. At any rate, I do not think there is a lot of metal in the water... but there seems to be just enough to plate out and make small stains here and there when pH and FC run high. The staining isn't significant, it is just enough to bother me.
I feel like an off season acid wash and trucked in clean water is in my future, but short of that...
1.)Polyyquat 60 -- will this alter my ability to test and maintain the pH? It seems like it may be a good insurance plan against algae given the high phosphates in my water... I don't see any other reason not to use it, but not sure what else I may not be thinking of.
2.)Metal Magic -- can I add a maintenance dose with FC at 4-5? If not it seems like the risk of algae outweighs the risk of staining given we are in a heat wave, and I probably need to wait till later in the season to dose again.
Thanks all!
I feel like an off season acid wash and trucked in clean water is in my future, but short of that...
1.)Polyyquat 60 -- will this alter my ability to test and maintain the pH? It seems like it may be a good insurance plan against algae given the high phosphates in my water... I don't see any other reason not to use it, but not sure what else I may not be thinking of.
2.)Metal Magic -- can I add a maintenance dose with FC at 4-5? If not it seems like the risk of algae outweighs the risk of staining given we are in a heat wave, and I probably need to wait till later in the season to dose again.
Thanks all!
Speaks volumes about pool store testing. I have never understood why very knowledgeable people here recommend pool store testing for metals, as if those tests will be better than the rest of their tests. Sorry, bit of a digression, point is that if you are removing brown stains with vitamin C then it's iron.
While I'm never a fan of putting yourself in a position where you need algae insurance, I understand metals in the water can cause some problems. Poly 60 will create a small FC demand, but compared to other non-metallic algaecides it isn't especially noticeable. It wouldn't be my option of choice, however. Personally I would rather take the route of phosphate removal first. There are liquid based tests if you would like to test for yourself (recommended) and I recommend avoiding any pool store variants because they are very watered down. SeaKlear and Orenda make much more concentrated formulas, but keep in mind that it might take time to get your level down and the doses will likely cloud the pool for a couple of days. Since you are using borates I'd also make sure your level is at least 50 ppm. Borates has some algaestatic properties, at the very least it shouldn't hurt.
Long-term though I'd consider options to possibly remove the iron if you can. Unfortunately that means intentionally turning your water brown so it can be filtered out using poly-fil, but if it can be removed then you wouldn't have to deal with either staining or playing a balancing act to prevent the staining. Might be something to consider in the time between the end of swim season and winter shutdown.
Thanks! This is helpful. Does the metal remover just add more phosphates though? I am willing to try removing them, but I feel like I have read that the Metal Magic breaks down into phosphonates... I don't know the biochemistry there and am curious -- sequestered metal bound to phosphate... is this algae food? My (pool store measured) phosphate levels seem to be much higher ever since I started sequestering metals. It is a tricky trade off...
I know that this forum does not believe in removing phosphates but your numbers are high. I have had high phosphates in the past and Orenda PR-10000 works quickly as effectively. The chart Orenda provides shows you what to add per 10,000 gallons.
It works quickly 2-3 days to clear higher prices Phosphate levels however it clogs my de filter. The Orenda temporally clouds the water and if I need a crystal clear pool I slowly reduce the phosphates instead of bombing the pool to remove all of them in 1 weekend. At 5.6 oz of Orenda in my pool I can reduce phosphates in my pool by 400 overnight. I have added as much as 16 oz the max dose per my pool at any one time and it could pool for a few hours but with diligent backwashing to keep my de filter working I get my clear water back over night. The next day the robot gets the gray fallout. No amount of backwashing clears the filter for more that a few hours. I usually treat phosphates Friday night and plan to run filter all weekend 24x7 backwashing every few hours during the day and first thing in the AM. At high levels there can be a little gray fine fall out. My robot with the fine filters get is and I’ve also brushed it and mixed it into the pool water and my de filter traps it. Whe.n I wake up after a phosphate treatment my jets are barely pushing and a quick backwash gets the. Going for a few hours. Then I’ll backwash again.
When cleaning the filter - I remove the grids from the filter housing and use a hose lance to get between the grids without removing them from the manifold. Clean the housing and reassemble. I can do that in 15 minutes.
It’s worked for me so far.
It works quickly 2-3 days to clear higher prices Phosphate levels however it clogs my de filter. The Orenda temporally clouds the water and if I need a crystal clear pool I slowly reduce the phosphates instead of bombing the pool to remove all of them in 1 weekend. At 5.6 oz of Orenda in my pool I can reduce phosphates in my pool by 400 overnight. I have added as much as 16 oz the max dose per my pool at any one time and it could pool for a few hours but with diligent backwashing to keep my de filter working I get my clear water back over night. The next day the robot gets the gray fallout. No amount of backwashing clears the filter for more that a few hours. I usually treat phosphates Friday night and plan to run filter all weekend 24x7 backwashing every few hours during the day and first thing in the AM. At high levels there can be a little gray fine fall out. My robot with the fine filters get is and I’ve also brushed it and mixed it into the pool water and my de filter traps it. Whe.n I wake up after a phosphate treatment my jets are barely pushing and a quick backwash gets the. Going for a few hours. Then I’ll backwash again.
When cleaning the filter - I remove the grids from the filter housing and use a hose lance to get between the grids without removing them from the manifold. Clean the housing and reassemble. I can do that in 15 minutes.
It’s worked for me so far.
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Which model salt water generator do you have and how many hours per day do you run it? You are on the lower level of FC for the TFP method. I share your same fears and I’m considering the swg to alleviate mine. I’m wondering why you don’t add some hours or run at 100 percent to increase the FC and stop your concerns. (I would have the same ones too)
On the FC level, you say FC levels are holding day to day, but at a level lower than you would like. You can supplement by adding LC and the increased level will hold for a time (based on bather load and UV exposure of your particular pool). The total daily FC loss will increase some measure with increased FC, but that supplemented higher level can hold for a time and may be worth experimenting with to see how your pool reacts, to add that bit of “insurance.” Just throwing out another potential option.