Yet another algae problem not clearing

[anderson110]

I have a 15' Intex round pool with a sand filter.

I opened the pool last Saturday, and my filter GFI had tripped a few weeks ago, and I'd dropped the ball on chlorine levels, and it was a terrible swamp. I mean terrible: clouds of solid algae swirling.

Over the winter I use trichlor tablets just to take maintenance hassle from daily to weekly or so, and then I'll just dilute if necessary if CYA has climbed while the pool is closed for the winter. Not a big deal, water is very cheap in my area. While the pool is open in summer, I maintain it daily with bleach as per the TFP approved protocol.

When I opened the pool, CYA was about 50, which was fine, TA 90, ph 7.2. All fine.

So I started shocking up to 20 ppm and I've held it there consistently for five days now. It is now holding chlorine fairly well. 2-3 ppm loss overnight. Continuing the shock process.

The problem is that while I did go from pea soup to your basic cloudy green pool, it does not appear to be progressing any further.

I've brushed at least daily, this usually stirs up more dead algae.

I've also vacuumed a few times to waste from the bottom of the pool, which does seem to be removing dead algae from down there.

But the pool just hasn't improved much in appearance over the past several days. Filter is running 24/7, backwashing a couple times a day.

I am considering shutting off the filter overnight to promote settling and then vacuum to waste first thing in the morning. It seems the sand filter is just not very effective at removing these particles.

Does that idea have any merit?

 

[jblizzle]

You could try this:
pool-school/add_de_to_a_sand_filter

But, what you are describing seems pretty typical for clearing a swamp with a sand filter.
You should be backwashing when the pressure goes up 20-25% of the clean pressure.

 

[anderson110]

Ok, first, some pics:

April 21:


April 23:


April 25:


Edit for April 28:


At this point I raised the shock level from 20 to 28:

Edit for May 1:


Progress! Still very cloudy, lots of sediment swirls up upon brushing, but a very clear color change when put against prior pics.

 

[anderson110]

And then one more question:

I see most people don't recommend draining and refilling. But I'm starting to wonder why not. Suppose the cost of water is not a consideration.

It's true that if you didn't treat your water well, the problem would come right back. But what if you continue the shock process as normal, while, say, draining 1/3rd (perhaps siphoning from bottom where the bulk of the sediment is) and refilling 1/3rd every other day or so?

Might that not speed this whole process quite a bit? I saw that recent thread where it took a guy a month to clear his pool using the traditional bleach/filter approach. I don't want to wait a month to get my kids back in the pool.

 

[jblizzle]

So your CYA was 50, but is that loaded puck floater still in the pool? Or was it 50 after you removed it?

How sure of that CYA test are you? I am surprised that the water has not turned more white with all the algae being killed; but then again it has only been 5 days and the whole process can take weeks.

As far as the draining question:
1. It can ruin liners
2. Pools can float out of the ground
3. What is the fill water and is there metal in it? Can your well support it etc.

Maybe none of those apply to you and you could drain, wash and fill.

If the pool was closed late enough and properly and opened early enough, then many people do not have this to deal with in the spring.

 

[anderson110]

So your CYA was 50, but is that loaded puck floater still in the pool? Or was it 50 after you removed it?

That first pic was when I first pulled the cover off. The floater came right out after I started adding bleach that same day.

How sure of that CYA test are you?

I did it pretty carefully using the TF-100 I bought last summer. While there's some subjectivity to "can't see the black dot", I used 50 as what I thought was the highest number it could be.

Probably worth repeating the test.

I am surprised that the water has not turned more white with all the algae being killed; but then again it has only been 5 days and the whole process can take weeks.

Yes, it's still greenish, which I was wondering about as well. But it's also holding FC fairly well (which it didn't for the first couple of days).

As far as the draining question:
1. It can ruin liners
2. Pools can float out of the ground
3. What is the fill water and is there metal in it? Can your well support it etc.

Maybe none of those apply to you and you could drain, wash and fill.

I have city water that seems fine as fill and is cheap. I pay a fixed cost through the nose, but usage is almost free: you can fill a 10,000 gallon pool and not notice it on your bill.

I think I'm going to try a lot of vacuuming to waste from the bottom to try to clear as much sediment as I can that way, and then refill whatever was lost in the water level.

If the pool was closed late enough and properly and opened early enough, then many people do not have this to deal with in the spring.

The pool was sparkling clear all winter, and I got complacent about it. And bam!

Lesson learned. This is only my 2nd try at this.

 

[jblizzle]

Likely then you just did not "open" early enough when the water warmed up and algae exploded when the FC dropped.

 

[duraleigh]

At this point, I think the issue is primarily your filter size and pump size. A larger filter would be faster and a larger pump would be faster, too.

That said, your current setup will work, it's just going to be slow Shutting off the pump overnight and vacuuming s-l-o-w-ly to waste the next AM might give you some real progress.

Keep your chlorine up and stay the course. Once clean, it will be easy to keep it that way.

You can certainly drain if you like but mostly you will drain water and not the stuff you are trying to get out. Vacuuming and filtering are better option.

 

[anderson110]

Likely then you just did not "open" early enough when the water warmed up and algae exploded when the FC dropped.

Yep. That's exactly what happened.

I just repeated the CYA test. 60 absolute worst case. I'll shock at 24 from here on out.

 

[anderson110]

You could try this:
pool-school/add_de_to_a_sand_filter

But, what you are describing seems pretty typical for clearing a swamp with a sand filter.
You should be backwashing when the pressure goes up 20-25% of the clean pressure.

Just added a little DE to the filter. We'll see if that helps.

 

[frustratedpoolmom]

I'm suspecting not enough chlorine. You should have seen a color change by now if you were hitting the appropriate target.

 

[anderson110]

I'm suspecting not enough chlorine. You should have seen a color change by now if you were hitting the appropriate target.

It's been held very consistently at the recommended shock value, as measured by the DPD test.

I'm not sure what else to do other than that.

There has been some color change. I think the photos show that.

 

[jblizzle]

The DPD or the FAS-DPD?

 

[anderson110]

The DPD or the FAS-DPD?

The one in the TF-100 with the graduated cylinder that says chlorine only.

 

[jblizzle]

With the powder ... that is the FAS-DPD

 

[anderson110]

At this point I'm wondering about my filter. I added DE to the filter, the pressure went up about 25%. Overnight, the pressure then decreased back to the clean pressure. Shouldn't it continue to rise if the sand/DE is catching particles?

Progress is basically undetectable over last few days. I moved the shock level up to 24 ppm to see if that helps. No changes.

April 28th

 

[duraleigh]

Don't start a new thread with the same question.....it confuses everyone. I deleted your other thread.

The last pic is VERY revealing....you still have a ton of live algae in the pool and will need more chlorine to kill it. Keep your FC up at 24 all the time...(it's ok to go to say 28 or so and let it drift down to 22 but no lower.

The intex pumps and filters are really poor at clearing a pool but that is not your primary issue....you need more chlorine held in the pool longer and the color will change and clearing will begin.

 

[anderson110]

Don't start a new thread with the same question.....it confuses everyone.

Err, what? If you are talking about my question about pump/filter, that was a new question, not really about algae (the topic of this forum) but about how to diagnose pump problems in general with respect to pressure changes.

I don't appreciate it being deleted. Please restore the question.

 

[jblizzle]

I think it was just merged into this thread. Much clearer to keep all your questions together so your whole story is known.

It is not normal your the pressure to drop overnight, unless you suction side got clogged. With that much algae in the pool, you need a lot more bleach and will have to clean the filter often.

Posted from my Droid with Tapatalk ... sorry if my response is short

 

[anderson110]

The last pic is VERY revealing....you still have a ton of live algae in the pool and will need more chlorine to kill it. Keep your FC up at 24 all the time...(it's ok to go to say 28 or so and let it drift down to 22 but no lower.

Ok, then, took it up to 28. We'll see if that changes things.

While brushing today I think I could see the brush head at the bottom of the pool for the first time, so maybe there is some progress, but it is excruciatingly slow.