Turning my algae farm back into a swimming pool

[mobilemike73]

Hello. Late last summer I was hospitalized and ended up leaving my newly installed pool unfiltered and unchlorinated from August until now. Needless to say it's a mess and this weekend I am planning to work to take it back so we can start swimming. It's a deep dark green.

Pool Details:
10,000 gallon above ground, vinyl liner, 22' Round
100lb Sand Filter
2HP Pump
K-2006 test kit restocked with new solutions one month ago

I have started circulating the water and am first adjusting pH to 7.6 before doing anything more. My next step is to start adding chlorine and continue testing as well as adjusting water quality to maximize results. I tested for CYA and the test water was barely cloudy and is lower than the minimum measurable level on the k-2006 test. I would appreciate any advice offered but here are some specific questions I have regarding my situation:

1) What's the highest level of TC/FC I can maintain without damaging the vinyl liner? Will CC affect the liner or just FC?
2) Should I add some CYA immediately or wait till the water is cleared?
3) Will my sand filter be able to clear the water or am I going to have to shut down the filter for a few days to let the particles settle and then vac out the debris?

Thank you very much for any and all opinions.

Mike

[PoolDoc]

Your pump is the most massively oversized pump, compared to the filter, I can remember encountering. A 1 HP AG pool pump is too large for a 100# sand filter! If it's really a 2HP pump, it would blow the algae right through the filter.

+ There's no answer to 'how high can you go without bleaching the liner'. I'm not sure if the liner makers know, but I am sure that if they do know, they're not saying! I can tell you it varies from maker to maker and liner to liner (within a single brand) and even from year to year, as the printing dyes vary. Reported, dark blue is the most susceptible color.

You need to post current test results, especially including CYA levels.

+ Once you work out a dose, you need to (a) put the pump on recirculate, (b) begin repeated doses of chlorine till it's ALL dead, (c) brush the heck out of the pool to stir up any remaining live algae, and then (d) let it settle and vac to waste.

+ You really also need to step down your pump. It's possible in many cases to put a 1HP impeller in a 2HP pump, and that would help, a lot. Also, most of the sand in your filter has probably been lost while backwashing, so you'll need to check that.

Good luck.

[mobilemike73]

Wow! I'm surprised that the local pool store would have set me up with more pump than needed. If anything I would have thought they would have undersized me, I purchased as part of a standard kit package priced pool with all the trimmings. I have thought about switching to a cartridge filter, I used to have one and really had sparkling clean water. Would getting a big filter help offset the overpowered pump? I'm not sure I'm up for swapping out the impeller. The label on the pump says 2HP but it seems to be doing ok filtering and I haven't lost any sand that I can see from backwashing. What do you think I should do?

So far so good on the pool. It's a milky white and the initial foam from all the oxidation of the algae has subsided. I put a total of 75ppm chlorine into the pool over the last 48 hours. Tonight after the sun sets I am going to shut off the pump and let it settle out.

My water chemistry is way out of whack and I am going for supplies this afternoon. I'm going to add about 10 lbs of baking soda to bring my alkalinity and ph levels closer to being in balance. TA is currently 30 and PH is currently 7.0. I'll post a complete set of results after this adjustment.

Thanks!
Mike

[PoolDoc]

Wow! I'm surprised that the local pool store would have set me up with more pump than needed.

Nah, it's standard. The wholesale cost difference between 1HP, a 1.5HP and 2HP above-ground pump is usually small. And, given the whole American 'bigger is better' ethos, the pitch, 'And, just for you, we're throwing in an upgraded 2 HP pump' is a sexy and effective sales line.

Offering a new-to-pools customer a 22" filter instead of a 18" filter is much less 'sexy'. Plus the 22" filter costs significantly more at wholesale.

For the most part, it's all about what will sell, and not what will work well.

[Watermom]

Wow! I'm surprised that the local pool store would have set me up with more pump than needed.

We see it ALL the time!

My water chemistry is way out of whack and I am going for supplies this afternoon. I'm going to add about 10 lbs of baking soda to bring my alkalinity and ph levels closer to being in balance. TA is currently 30 and PH is currently 7.0.

Use 20 Mule Team Borax (laundry aisle at Walmart) to raise the pH. Maybe a third of a box at a time. Retest, redose as needed. Don't add 10 lbs. of baking soda all at one time. A couple of lbs at a time, let it circulate a few hours, retest and redose gradually. Smaller doses are better than one big dose.