Phosphate problem?

[maureenq]

As I do usually once a month, I go to my pool company (not Leslie's much more knowledgeable or up to this point they have been)and have them test my water. I do have the recommended kit here and use that in between. With all of the rain we are having here in the Northeast, the pool company results were:
.1 for chlorine (I know this is low and have put in bleach already, I normally do not let this ever get this low)
7.8 for ph (a little high, but with rain I am struggling to keep at 7.5)
150 hardness (pool co. recommends add 20 lbs of hardness control
92 alkalinity (I know this is low, so I guess I will use the pool co. recommendation of adding 10 lbs. of alkalinity rise
60 CYA (good)
2500 - phosphate reading (pool co. says it should be 0-500)

In the five years that I have maintained my pool with Bleach method, never have I had this phosphate issue. I have never had an issue with alkalinity either, but makes sense with the rain we have been having. So my question - should I use this phosphate down type product, is this a legitimate problem or just a way for the pool company to make more money?

Thanks for your help!

[waterbear]

Speaking as someone who has worked in pool stores it is not needed and is a money maker for the store. However, you do need to make sure you maintain your FC at the proper level for your CYA at all times. If you are doing that then no worries!

[aylad]

The phosphate remover is absolutely not needed in your case--it is purely profit for the store!! Also, I would leave your alk alone at 92, unless you're using trichlor pucks, which I would guess you're not since your pH is high. Also, if your pool likes to "settle" at pH of 7.8 (mine does), then often you are better off just leaving it alone instead of trying to fight it. I leave mine alone and let it stay at 7.8 unless I have an algae problem and need to shock it.

What kind of pool do you have? If it's a vinyl pool, then don't waste your money on the extra calcium either, since you won't need it. (It makes pretty good sidewalk de-icer if you've already bought it and thrown away the receipt!) If those were my numbers, I would add chlorine to about the 8 ppm level and go swim!

Janet

[Charlie]

I've been using Phosphate remover every other week (~1 oz) to keep it below 100. This is the first year that my pool has zero algae. I have a salt water pool.
FC:2.5
CC:0
pH:8
TA:120
CH: 280
CYA: 80
Salt: 3200
Phosphate: <100

I don't use Phos-Free that was recommended by Leslie's because it adds CH. I bought one made by HASA, and its called Phos Out. Stuff works great.

[CarlD]

Charlie:

If you need to use a phosphate remover constantly, something else is wrong with your pool chemistry. Most of us NEVER use it and rarely, if ever, have an algae problem. I've never measured my phosphates and have had very few algae blooms over the years, and never had a major one, ever.

Phosphate Removers are the latest gimick at pool stores to get people to spend money constantly on something they can't get anywhere else. They measure your water and say "Oh, your phosphate level is high--you need this chemical--every week!" For a while it was "Total Dissolved Solids". A couple of years ago it was the Nature2 erosion systems. An ongoing one is selling calcium to vinyl pool owners (calcium is useless in a vinyl pool). If one in a thousand pools actually needs a phosphate remover, that's a lot.

I THINK you said you are using an SWG. With your CYA at 80 and your FC at 2.5 and your T/A at 120 and a pH of 8, I'm not surprised you are fighting algae. If you don't have an SWG, than I'd be shocked if you did NOT have an algae problem with those numbers.

1) Let's start at the end: pH=8. This kills most of your chlorine's effectiveness. At even 7.8, chlorine is far less effective at killing stuff than at 7.2 or 7.3. So you MUST get your pH under control. This alone may solve your algae problem, ESPECIALLY if you have an SWG.

2) Your FC is too low for your CYA--it's 2.5 and your CYA is 80. Normally, you need an FC of 5 to 10 for that CYA or you'll get algae. However, if you have an SWG, you may be OK at 2.5, but 3.0 is probably safer--I'm not the SWG expert here--check the owner's manual.

3) Alternatively, you can lower your CYA to between 30 and 50 and keep your FC between 3 and 6. But if you have an SWG, your CYA level is probably correct, but you still need to set the SWG to a higher FC level.

4) Your T/A is fine--if you don't have an SWG. If you do, you should keep it lower--around 80-90.

Take all these steps and you can stop wasting your hard-earned money on the phosphate removers.

[waterbear]

Charlie:

If you need to use a phosphate remover constantly, something else is wrong with your pool chemistry. Most of us NEVER use it and rarely, if ever, have an algae problem. I've never measured my phosphates and have had very few algae blooms over the years, and never had a major one, ever.
Gotta agree with Carl here! Phosphates are usually NOT the limiting factor in algae growth! Low FC is!

Phosphate Removers are the latest gimick at pool stores to get people to spend money constantly on something they can't get anywhere else. They measure your water and say "Oh, your phosphate level is high--you need this chemical--every week!" For a while it was "Total Dissolved Solids". A couple of years ago it was the Nature2 erosion systems. An ongoing one is selling calcium to vinyl pool owners (calcium is useless in a vinyl pool). If one in a thousand pools actually needs a phosphate remover, that's a lot.

I THINK you said you are using an SWG. With your CYA at 80 and your FC at 2.5 and your T/A at 120 and a pH of 8, I'm not surprised you are fighting algae. If you don't have an SWG, than I'd be shocked if you did NOT have an algae problem with those numbers.

1) Let's start at the end: pH=8. This kills most of your chlorine's effectiveness. At even 7.8, chlorine is far less effective at killing stuff than at 7.2 or 7.3. So you MUST get your pH under control. This alone may solve your algae problem, ESPECIALLY if you have an SWG.

Actually wth CYA iin the water the pH effects on chlorine's effectiveness are much less important. What is important is that a pH above 7.8 is too high for a SWG to work effectively. I have seen units stop producing chlorine at high pH. Keep the pH below 7.8 at all times. If it rises too fast then lower the TA to about 70 ppm and consider adding 50 ppm borates to the water.

2) Your FC is too low for your CYA--it's 2.5 and your CYA is 80. Normally, you need an FC of 5 to 10 for that CYA or you'll get algae. However, if you have an SWG, you may be OK at 2.5, but 3.0 is probably safer--I'm not the SWG expert here--check the owner's manual.
Carl, no worries, I am! (SWG expert that is!)
FC should be 4-5 ppm with CYA of 80 and a SWG for algae free water BUT pH MUSt remain below 7.8!

3) Alternatively, you can lower your CYA to between 30 and 50 and keep your FC between 3 and 6. But if you have an SWG, your CYA level is probably correct, but you still need to set the SWG to a higher FC level.
Keep the CYA at 80 with a SWG or your will have pH control problems!

4) Your T/A is fine--if you don't have an SWG. If you do, you should keep it lower--around 80-90.
Even 60 or 70 ppm if you are still having pH control problems!
Take all these steps and you can stop wasting your hard-earned money on the phosphate removers.

Hope this helps.

BTW, Charlie, wherever did you get the idea that PhosFree adds calcium hardness. ALL phosphate removers that are lanthanum based are either lanthanum chloride, lanthanum sulfate, lanthanum carbonate, or a mixture. The first two form lanthanum carbonate in the water. Alum floc will also remove phosphate.

[CarlD]

Thanks Evan. My knowledge of SWGs is limited so I can only provide what I've learned from the SWG users.

I know that pH of 8 is very bad if you don't have an SWG because the chlorine is far less effective, but I didn't know it's even worse if you do have an SWG because it will stop producing chlorine!

I knew that a CYA of 80 is appropriate for an SWG, but not therefore, the correct FC--I would normally recommend an FC of 5-10, and, while it CAN be lower, clearly it can't be more than a PPM lower than the minimun non-SWG pool.

I also knew the lower T/A was better--but, again, not at a level even below the normal minimum.

I DO know that rising pH is very common with SWGs, and that the lower T/A can inhibit that. It's a bit counter-intuitive but it does work.

Again, thanks to Evan for helping me with that.

I just came back from vacation to VERY low pH--it took a full box of Borax and a full box of Washing Soda (soda ash--same as "pH Up!", but cheaper) to get pH back into the safe zone. It wasn't unexpected as I used Tri-Chlor tabs to help maintain my FC while we were away for 2 weeks. CYA isn't very high as the constant rain has washed it out--but with the solar cover one there's been no aeration to reduce the increase in acidity the tri-chlor generates.

Still the water is now fine and warm enough to swim, but the days are getting shorter and the nights are going down to 50 or lower so my solar panels are working VERY hard to keep the water over 80. I'm hoping for a dry, sunny September after a rainy summer so we can stretch the season a little--we haven't swum much this year, and the water only reached 90 once--usually in early August it passes 96 and reaches 98--like a giant hot tub!

Soon, it will be time to close again as another season ends....I'm just not that big a fan of autumn!

[waterbear]

Thanks Evan. My knowledge of SWGs is limited so I can only provide what I've learned from the SWG users.

I know that pH of 8 is very bad if you don't have an SWG because the chlorine is far less effective, but I didn't know it's even worse if you do have an SWG because it will stop producing chlorine!

This is only really true in an unstabilized pool. Once you have CYA in the water the effects of pH on chlorine's effectiveness (whether it's in the form of hypochlorous acid or the much less effective hypochlorite ion) become much less important since most of the chlorine is now in the form of chlorinated isocyanurates and pH has much less impact on the activity of the chlorine. Chemgeek knows the actual numbers but bottom line is that the old 'chlorine is more effective at a lower pH' is another one of those industry TEKTATs (Things Everone Knows That Aren't True) when you are talking about a stabilized pool.
http://www.poolsolutions.com/tips/tip72.html

[chem geek]

I have graphs here in The China Shop. However, the fact that the active chlorine concentration without CYA drops so dramatically at higher pH is a bit of a moot point since its absolute concentration is so much higher to begin with because there is no CYA to moderate it.

As Evan wrote, the effect of pH on active chlorine is significantly reduced when CYA is present. With an FC of 3 ppm and no CYA, going from a pH of 7.5 to 8.0 goes from an active chlorine (hypochlorous acid) concentration of around 1.5 to 0.7 or roughly a 50% drop, but with 30 ppm CYA in the water it goes from 0.042 to 0.036 or a drop of around 14%. CYA is like an active chlorine buffer just like the carbonates (and borates) are a pH buffer.

As for a lower TA having the pH be more stable when using hypochlorite sources of chlorine, the simplest way to understand this is that the carbonates portion of Total Alkalinity (TA), which is mostly a measure of bicarbonate, has TWO effects: 1) it is a pH buffer so higher TA is more resistant to changing pH from outside influences and 2) it is a SOURCE of rising pH itself where higher TA results in faster carbon dioxide outgassing that causes the pH to rise. This latter effect outweighs the former so as ironic as it may seem lowering the TA leads to greater pH stability when the reason for that rising pH is the TA in the first place (if the reason is primarily from something else, such as plaster curing, then a higher TA might be helpful up to a point).

Richard