Phosphate Rise and Borates


Bronze Supporter
Jul 13, 2015
Huntingtown, MD
I added 20 Mule Team Borates and Acid (per the excellent procedure posted on TFP website) summer last year to get me up to 30 ppm using LaMotte borates test strips. Happy with the result, as it seems to buffer my pH swings to the high side. Less acid used over the long haul. Hard to estimate the other benefits and my two Maltese dogs don't go anywhere near the dogs drinking pool water not an issue LOL.

This year I noticed my Phosphates went up from 400 to 1200, between closing 11-1-16 and opening 3-28-17. Everything else right now is in perfect balance. The water looks great...albeit at 65 F still.

I would guess that adding 20 Mule Team Borax (from good old Wal-Mart laundry detergent aisle) did not cause this raise in Phosphates...and I wonder what could. Fertilizer used on grass nearby? Over-spill from large broadcast fertilizer spreader? Leaching thru the nearby ground (NOT!!!) It seems highly unlikely given the amount of 10-10-10 fertilizer required to raise it to 1200 from 400.

How about sprinkler water from a 250' deep underground well? One of my heads does over-spray a strong mist or momentary stream in to the pool, depending on wind direction and velocity. Hmmm. Maybe I should test my well water?

Bad test result from the Pool Store guy?

I'm not overly worried about the Phosphate level....just curious what made it change from 400 to 1200 over the winter. I'm not going to rush out and buy the phosphate removal kit (of course recommended by my Pool Supply Dealer up the road)...I know how to keep the algae at bay....

Thoughts? :confused:


LifeTime Supporter
Mar 13, 2015
Savannah GA
I would be inclined to believe the tester was the reason. Being that we know how poorly most pool store testing is, why believe the phosphate numbers, and since chlorine prevents algea regardless I would only ask for metals or salt tests at the pool store.


Bronze Supporter
Jul 13, 2015
Huntingtown, MD
I really only use pool store tests for Salt too. And to see how much differences there are between the TF-100 and their numbers. They have some automated machine that spits out a report from one vial of water....way less than 5 ounces. I'm going to ask what they use next time I go...just out of curiosity. I buy liquid 31.45 acid there also, as it is less than the Home Depot paint department acid.

You know: I used to live in St. Pete FL 5 years ago...and acid was maybe $3/gal. I move to S. MD and acid is closer to $7/gal. Wow.


Mod Squad
TFP Expert
Platinum Supporter
LifeTime Supporter
In The Industry
Apr 1, 2007
Sebring, Florida
Phosphates are of no consequence to a normal pool. If your other parameters are correct, you are good to go.....ignore phosphates


TFP Expert
Apr 19, 2013
Sacramento, CA
I'll refine Dave's comment above a bit. If you are getting regular algae outbreaks while maintaining your pool at close to TFP standards then you may want to consider reducing your phosphate concentration.

Well water or lawn runoff are likely culprits for your over the winter rise. I would take your well water in for testing.