Algae an borates

[cschnurr]

Last week my pool was slightly green, and every morning I found small traces of what look like alge. I brushed the pool and cranked the SWG to 100% with the pump 24/7 and it seemed to keep it at bay, but didn't seem to improve significantly. My CYA is at 80%. When I turned the SWG off overnight, I never had any decrease in FC.

I decided to shock last night up to FC=20ppm (dilution method) and brushed the pool. I turned the SWG off and let the pump run 24/7 .

This morning I had no detectable decrease in FC yet had a thin film on the bottom only detectable when I brushed and traces of yellowish deposit on stair. I turned the SWG on 100% and am now vacuuming.

My measurements are
FC 20
CC 0
ph 7.6
CH 250
CYA 80
TA 110

I hoping this will clear my problem.

I have a couple questions about algae.
1) Since my FC held, am I good to go, or does the presence of the film on the bottom and trace deposit on the stair indicate I still have algae?

2) When shocking, I know I should brush and vacuum. I understand brushing gets algae off the bottom so it can mix with chlorine, but it also gets dead algae off the bottom so vacuum won't pick it up. How can I tell the difference between live and dead algae so I know when to brush, and when to vacuum.

3) I seem to see deposits in exactly the same place all the time.
The exact same 2 inch area on one of the steps, and along the lip where the shallow end inclines to the deep end. Is the reason for this due to water circulation pattern or something at that location that feeds the algae?

4) I'm considering adding borates. From what I understand I need 36.8 pounds of 20 Mule Team Borax and 281 fluid ounces of Muriatic Acid (31.45% Hydrochloric Acid) per 10,000 gallons to raise the Borates level to 50 ppm and re-establish pH.

I am hesitant for a couple reasons. I have a dog that drinks from the pool, and I don't know where to get the borate test strips in Canada. I am the original owner and never added any borax to the pool.

Would it be worthwhile putting in 60% of the borax and acid to get borates to 30ppm without test strips. This way I'm guessing would be better for the dog and I wouldn't have to worry about over shooting 50ppm.

[cschnurr]

I vaccumed the pool with the SWG on 100% for the entire day on Sunday.
I kept the pool at 20ppm on Sunday.

Sunday night, I turned the SWG off so I could monitor Cl consumption.
Sunday night 20ppm, Monday am 20ppm
Monday night 15ppm, Tuesday am 15ppm
Tuesday night 11ppm, Wednesday am (didn't measure)
Wednesday 7:00 (tonight) 8ppm.
Barely 50% drop over 3 days, I'd expect this consumption without algae.
SWG off the entire time. Weather was cooler High mid 70s and mostly sunny.

When I came home from work Wednesday, the water looked pretty clear from the back door, (Saturday before shock, it had a greenish tinge). But when I got closer, there were large deposits on the bottom of my pool (and a dead frog and mouse in the skimmer). I would have thought the deposits were algae, but is it possible it was dead algae?

I vacuumed the deposits to waste. The water looks pretty clear, I can read the 1/4" print on my vacuum in the deep end, no sign at all of any greenish tinge.

I test with a Taylor K2005 kit
FC 8-9ppm (measured twice: dilution 2:1 and 3:1)
CC (slight colour change but barely discernible)x3?
pH 7.6
TA 120
CH 280
CYA 80 (measured a week ago, but ran out of reagants)

As a sanity check, I also used test strips which are consistent with my measurements.

This may be totally unrelated, but last year I had a water bubble behind my liner in early August, and had an agae problem at the same time. There was no water behind the liner when I opened this year, but the water bubble is back again now and I have algae.


Any advice?

[cschnurr]

Wedneday night Cl measured 9ppm,
Thursday am still at 9ppm, with no sign of any deposits anywhere.

I'm thinking I'm either fighting pollen (as mentioned on other threads) or am on the brink of algae blooming below 8ppm.

I know this is not in line with POP, but I've hosting neighbourhood party coming on Sunday. Since whatever the deposits were are gone, and didn' seem to consume my Cl, I'm thinking I'll maintain Cl around 10ppm for the weekend, after Sunday let it drop to my 'normal' value around 5. If algae blooms I'll shock then.

[aylad]

Your plan sounds good to me...if you're holding chlorine overnight and have no abnormal consumption during the day, and if your water is back to blue, I would just hold the Cl a little high until your party is over, and shock afterward just to kill any remaining "nasties". I think the film that you originally found on the bottom and sides was residual live algae, which can be present with no CC reading or huge drop in chlorine. I also think that since the film disappeared and the deposits appeared after an extended shock, that you probably had deposits of dead algae on the bottom and correctly vaccuumed them to waste.

I strongly suspect that you're either fighting pollen (don't remember offhand where you are but we're fighting an ongoing battle with it in Louisiana this summr), or possibly some sand blowback from your filter. Is there any other way that dirt might be introduced into the pool? Usually when the deposits start showing up in the same places, especially if they are near the return jets, it's more a matter of dirt or pollen that is settling there due to water movement. Algae usually deposits itself a little more randomly, and takes up larger spaces.

Janet