Tough Algae even with high chlorine

[Rvjames]

Hello,

I have an IG 24,000 gallon vinyl pool with Hayward's sand filter and a 1 1/2 hp pump.

Two weeks after a massive thunder storm I had Algae bloom and I shocked the pool using 2lbs of calcium hypo chloride bags tested in the morning the chlorine was over 8 in the FAs-dpd kit k-2006. The pool did it get clear and the algae became worst in next two days so I added another 2 gallons calcium hypo chloride.

It has been two weeks and still there is residue of algae even though chlorine level is way above what I can measure with the kit, I do have tri chlor tablets in the inline chlorine feeder. *This morning I found lot more algae but chlorine level is still dark purple above the max color on the kit.*

I am ate lose down know what more I can do, the kids are eager to jump into the pool on the 4th and w have friends coming over it is going to be sad to see a green cloudy pool. What do I need to do to get it to some decent level in two days. *I will post full test results tonight but I am worried that the high chlorine level will bleach and show wrong readings. I have been brushing and running the pump almost 20 hours a day.
Help please

[aylad]

Hi, and welcome to the forum!!

If you're using a FAS-DPD kit, then you can accurately measure chlorine levels up to 50+ ppm. (This is the test where you take the 10 mL water sample, add a scoop of powder to it, swirl to mix, then add drops until the mixture goes from pink to clear). This form of testing won't bleach out, unless you've got chlorine levels of 90+ ppm, and if that were so, you wouldn't have algae!! I suspect that you've been using the OTO kit, which just uses 5 yellow drops to measure chlorine and then you have to compare it against a scale. However, I don't know what chlorine level you could have that would turn the result purple, unless you're using the red drops--and in that case you're measuring pH instead of chlorine.

In order to clear up the pool, we're going to need to know your stabilizer (CYA) level. I'm betting it's pretty high, if you always use trichlor tabs. When we know your CYA level, we can tell you what level to raise your chlorine to in order to clear up the green . When you raise your chlorine to that shock level, you're going to need to hold it at that shock level until the green completely clears, and until you can measure chlorine at night and again the next morning and not lose more than 1 ppm. Only then can you let the chlorine come back down and not expect to see algae growing again. So....test for your CYA, post the number, and we'll help you go from there.

[BigDave]

@aylad: I'm pretty sure the poster has a DPD color match kit. CL reads as shades of purple on a color comparator.

@Rvjames: You really will need the K-2006 to clean up the mess you have brewing. My guess: you've been using trichlor pucks in the feeder for quite some time and your CYA is quite high. Please order a K-2006 (accept no substitutes) and review Ben's Best Guess Chart to see the relationship between CYA and required chlorine levels.

The short of it is: you're going to need alot more chlorine (let's stick with plain, unscented bleach or liquid chlorine - both are sodium hypochlorite solution) and a way to test high chlorine levels and CYA levels. While waiting for your K-2006 (you have ordered it, right?), you can see if your local wall mart carries the HTH 6-way drops kit (check availability). If they do, pick one up, it is compatible with the Taylor K-2006 and will let you measure CYA.

[Rvjames]

Thank you both...

I am using a kit that I bought from Leslie's the brand is taylor it has the ability to test TC,FCC,PH,ACID AND BASE DEMAND, TA, CA and CYA.

I tested my CYA and it is at 80.

The chlorine test does change to purple, I am adding 5 drops of the DPD reagent #1 and then adding reagent 2 immediately the color becomes purple which is darker than the color at 5 in the testing unit. How do I get proper reading on the chlorine level.

The pool has turned to worst from this morning and we are having a heat wave in the Northeast.

Your help is much appreciated.

Thank you

[aylad]

If your CYA is at 80, then you need to bring your chlorine level up to 20 ppm and hold it there by testing/adding more chlorine as necessary to maintain that high level. You need to hold it there until the green clears up, and you can go from one night to the next morning without losing any chlorine. Pump and filter need to be running 24/7, cleaning the filter as the pressure indicates, and the pool needs to be brushed daily, preferably right after a chlorine addition. You're going to need FAS-DPD testing for this--if you'll take a look at the testkit link in my sig, the K-1515 is the only standalone test you would need to make your kit a true FAS-DPD kit and would make this a much easier project for you.

[PoolDoc]

Kit options:

HTH 6-Way Test Kit @ Walmart (OTO chlorine test)
Taylor K2006A (3/4 oz bottles) @ Amazon
Taylor K2006C (2 oz bottles) @ Amazon
Taylor K-1515 FAS-DPD @ Amazon -- complete K-2005 kit.

[Rvjames]

I am ordering the k1515 kit meanwhile based on the guidelines on the test kit which says I need to add 5 gallons of 12% chlorine shock I added 5 gallons of Buckman's liquid shock which has 12.5% sodium hypochlorite at 6:00 PM. To be really safe I Dded another 3 gallons of the same T 9:00PM. Have bee brushing every 30 minutes Nd have the pump running from the main drain t the bottom.

I will post the results in the morning, but don't know how to test accurate TC with the kit i have which can only match color which is T the maximum of 5 (purple).

Thank you again for all the help.

[Rvjames]

I ordered the 1515 kit.

Added 5 gallons of Buckman's liquid shock with 12.5% sodium hypochlorde at 6:00pm then brushed it thoroughly. To be safe I added another 3 gallons of same shock and pump has been circulating overnight.

This morning at 7:00 tested chlorine the color is off the chart purple so using the instructions on the kit first diluted 1:1 pool water and tap water still color was off the chart so diluted 1:4 (1.8 ml pool water and filled with tap after up to 9ml) the color is between 3 and 5 so multiplying lets say 4 by 5 the chlorine is around 20ppm.

It is going to be a hot day above 90 should I add couple more gallons of shock to maintain above 20ppm to be safe? The green is still evident the algae seems to be still alive in the water. What do I do?

Kids are disappointed that hey can't jump in tomorrow during the 4th party

Thank you for your help.

[BigDave]

I agree with Aylad - you need the K-1515 FAS-DPD. As soon as you use it, you'll know why.

For now, while you wait for the K-1515, to get your shock process going, you can use the dilution method to read FC and TC. You'll need distilled water, the Taylor instructions say tap but that will foul your test.

You appear to have a rebranded Taylor K-2005, if it's recent, the chlorine comparator tube is marked on the side - 1.8ml, 4.5ml, and 9ml. You usually fill to the 9ml mark when testing. Fill the chlorine comparator tube to the 1.8ml mark with pool water then add distilled to the 9ml mark. Test this diluted sample for FC and TC and multiply the results by 5. If you don't have the graduated comparator, you can do the same by mixing 1 measure pool water with 4 equal measures distilled water, test and multiply by 5 (this is the CarlD shot-glass method). Dilution testing loses accuracy but will get you started, you still need the K-1515 FAS-DPD.

Please test and report pH, TA, and Calcium Hardness as well. If your CH is relatively low, you can use calcium hypochlorite to reach and maintain shock level but if it's high, you have to use bleach / liquid chlorine.

Follow aylad's instructions for shocking your pool - it will clear.

[PoolDoc]

It is going to be a hot day above 90 should I add couple more gallons of shock to maintain above 20ppm to be safe? The green is still evident the algae seems to be still alive in the water. What do I do?

Kids are disappointed that hey can't jump in tomorrow during the 4th party

OK, I'm going to give a bit of 'off-spec' advice. But please READ what I write VERY carefully, and make sure you understand. Here are the conditions my advice is based on:

1. a CYA level of 90 ppm.
2. that you will USE either an OTO (yellow drops) test kit OR the K-1515 to test chlorine levels before anyone swims.

OK. On to the advice:

Algae in pools creates 4 hazards:

• Loss of visibility
• Loss of chlorine
• Slippery / slimy conditions
• Hazardous organism growth

You can deal with the last 3 conditions with sustained high chlorine conditions AND by brushing and vacuuming, to make sure that there are not algal 'safe havens' created by piles of algae or goop.

So, here's the deal. If

• you vacuum and brush to make SURE there are no piles of goo, AND
• you maintain OTO orange or K-1515 20+ ppm chlorine levels today AND tomorrow, AND
• you maintain chlorine levels BELOW OTO brown or K-1515 40+ ppm chlorine levels tomorrow, AND
• you maintain constant EYEBALLS ON SWIMMERS with a continuous head count, AND
• you warn people that new Lycra swimwear perish in your pool,

THEN, your kids can swim tomorrow.

The high chlorine will deal with the slime and pathogen and stop any NEW algae growth.

Caution: People are MUCH more chlorine-resistant than Lycra swim wear, so if someone shows up in a new Gottex swimsuit, that costs $10 per square inch of fabric used, you need to tell them to swim naked, or stay out of the pool. You can't even tell them to 'swim at their own risk' because if they do, they may end up swimming naked! Fashion Lycra has very poor chlorine resistance, at best. And Lycra swimwear, once the Lycra is gone, turns into loose nylon bags that will literally float off a swimmer. (Got some funny stories about commercial pools, but no time now!)

You might want to warn people to avoid swimming underwater with their eyes open; it may, or may not, be a problem.

But, you must, must, must watch the kids. I'm a former lifeguard instructor, and I hate going to pools or swimming areas where I see kids who are weak swimmers and who are NOT being watched closely. Add cloudy water, and my stress level goes through the roof. As a family (all lifeguards or former lifeguards), we avoid swimming where we'll see people swimming dangerously. I simply cannot relax and enjoy myself.

I would STRONGLY suggest having a dedicated parental 'watcher' who has NOT enjoyed any supplied alcoholic beverages, but who will constantly watch the kids while swimming. And keep the kids out, when no one's watching. Cloudy water is VERY often associated with drownings in shallow water.

But, if you can live within those guidelines, your kids can swim, not with perfect safety, but with what I consider to be an acceptable level of risk.