Problem only when pump running

I have what I think is mustard algae. Treated the pool with Yellow Out. Put all tools, hoses, etc in pool during treatment. Vacuumed to Waste. Next day, still there.

This is where it gets interesting:

Treated again, vacuumed to waste. After vacuuming, left the pump off for 3 days. No Algae! Turned the pump back on Filter setting....next day, full of algae.

Again vacuumed to waste then turned pump off for three days. No algae again. Then turned pump back on, this time on Recycle. Next day, full of algae.

I had the plumbing pressure tested. Guy said no air leaks. So where is the algae coming from???

Also, I seem to get a lot of dirt in the pool. My sand is synthetic (thus blue) so it is not coming from filter. And I have a large pool deck, far away from any dirt or sand.

Need help or I will soon make my pool an 18x36 tomato garden.

Synthetic sand does not prevent algae growing in your filter.

After 2 - 3 doses of Yellow Out, your pool is likely gonna be a mess. Don't count on getting relief quickly or easily. In my experience, both Yellow OUT (ammonia based) and Yellow Treat (bromide base) are a 'devil's bargain': you get what was promised, but you pay for it in the end!

1. I'll assume 24,000 gallons of for a 18x36 IG pool w/ deep end: PF = 5. Each gallon of PLAIN 8.25% bleach will add about 3 ppm of chlorine.

2. Go to Walmart and get 16 gallons of PLAIN 8.25% bleach, 4 boxes of 20 Mule Team borax, plus a cheap OTO / phenol red test kit (yellow / red drops).

3. Test your pool's pH. Remove ANY trichlor from your skimmer, any feeder, gizzmo or "FROG".
+ Turn your pump on.
+ Add 2 gallons of bleach THROUGH the skimmer.
+ If the pH (tested earlier) was 7.6 or lower, add 1 box of borax, SLOWLY to the skimmer.
+ Wait 1 hour. Retest pH. If still 7.6 or lower, add a 2nd box of borax.
+ Wait; test; repeat as needed.
(You want pH to be 7.8 or ABOVE while cleaning up the Yellow OUT mess -- otherwise you'll get smelly, irritating, and even toxic chloramines during clean up!)

4. Once pH is up, pour 4 MORE gallons of bleach THROUGH your skimmer.

5. That evening -- at least 1 hour after the first dose -- test your chlorine again. If the chlorine is not DARK yellow to orange (not shown on kit) add 4 more gallons of bleach. Check chlorine test 5 seconds after adding drops, and again after 2 minutes. Note difference. (If chlorine is ORANGE, at 5 seconds OR at 2 minutes, do not add more bleach.)

6. Test your chlorine level the following AM. If chlorine is medium yellow or lower, retest pH. Add more borax if needed. Add chlorine if test shows:
+ no chlorine => 4 gallons
+ light to medium yellow => 2 gallons
+ dark yellow => 1 gallon
+ orange => skip dose.

7. Repeat #6 that evening.

8. Retest chlorine following AM. Recycle steps 5 - 6


Continue dosing, per above, till chlorine levels remain unchanged overnight. Keep pH high until this happens.

. . . MEANWHILE. . . order a Taylor K2006 test kit from Amazon (link in my blue signature block). You will need this kit to make things right. Read the "Best Guess" page (linked in block) for a part of the explanation why.

Post your results, as you get them, so we can modify the process if needed.

Thanks for the great info and advice!

But I still can't figure out why the problems only occur if the pump is running (whether on Filter or Recirculate). If there is no algae when the pump is not running, where could it be? It would have to be in the pipes since it makes no difference if the water is being filtered or not. But where in the pipes? What could hold enough volume of algae to cover the entire pool in 12 hours?

I would think that I had some breach in the pipe(s) that was causing this. But as stated, I had the pipes pressure-checked and the guys said no breach.

Any additional help would be appreciated.

Quote:

---

Originally Posted by PoolDoc

. . . MEANWHILE. . . order a Taylor K2006 test kit from Amazon (link in my blue signature block). You will need this kit to make things right. Read the "Best Guess" page (linked in block) for a part of the explanation why.

---

1. I'm not sure exactly what's going on. Some bits of your description don't add up -- but that's not uncommon: if you were a pool expert, you wouldn't need to ask us.

2. TEST the pool water and we'll know more. Otherwise, we're really just wasting time guessing without information.

3. REGARDLESS of the cause, chlorine will kill the algae.

4. Algae is NOT getting INTO your pipes from a crack or a leak.

Again, get us the basic info and we can start trying to figure just why this is happening. But I'm not going to a lot of time into speculating unnecessarily, when we're still lacking basic info.

Quote:

---

Any additional help would be appreciated

---

You've gotten the help you need, but it's up to you whether you take advantage of it, or not.

Good advice; basics first. I will start the treatment and post results.

Thanks

ok.