Why so much dirt at the bottom?

Fronzizzle

Active member
Jun 29, 2017
34
Augusta Township, Michigan
Hello all,

I'm still somewhat new at pool ownership and have a question. We have an above ground, oval pool that is 34' x 19', 4' deep. There is no bottom drain, just the skimmer. I'm using a Hayward Pro Series pump & sand filter.

We are starting our 3rd season, and ever since we moved in we've had a really hard time keeping the bottom of the pool clean. We vacuum all the time, but it seems like right after we finish we see more dirt. Using information on this forum and the booklet that came with our Taylor pool testing kit, our water chemistry always seems to be where it should.

This is the first year we've opened the pool ourselves, and the bottom was really dirty. We've vacuumed it three times and it still looks bad. I know the vacuum is working, we've checked the suction and after X amount of minutes our pressure goes up and we have to backflush the filter. I suspect at least part of the problem is that there is so much dirt that the vacuum is picking some up and then just stirring around the rest, which then immediately resettles.

Our water is crystal clear right now, and the pump/filter runs all day with no issues or pressure changes. I did the OCLT test, we lost 1 PPM from 7 PM to 7 AM. It rained all night, not sure how that will affect the results.

I'm not sure if it's a matter of just vacuuming more often or something else. Our land is wide open on 3 sides - no trees anywhere close - but the wind can bring in a lot of dirt, I'm sure.

My filter is on a timer and I currently run it from 11 AM - 8 PM every day.
 

mas985

TFP Expert
LifeTime Supporter
May 3, 2007
12,800
Pleasanton, CA
When the filter pressure goes up that quickly, it is usually an indication of a chemistry issue.

But before we can help, we need to know a bit more about your setup. Please read this: Read This BEFORE You Post - Trouble Free Pool

Doing the OCLT is a good first step but we would also need to know the current chemistry test values to assess if it is an issue.

What you may be vacuuming up is dead algae and if you have a sand filter, it may not be capturing all of it. So again, understanding your setup is very important.
 

Casey

TFP Expert
LifeTime Supporter
Apr 16, 2007
10,929
SW PA
You could have algae. 1ppm loss in the OCLT suggest you may need to complete a full and thorough SLAM.
 

duraleigh

Admin
Mod Squad
TFP Expert
Platinum Supporter
LifeTime Supporter
In The Industry
Apr 1, 2007
32,859
Sebring, Florida
See if you can pick up that "dirt" in your pool between your thumb and forefinger. I bet it just whooses away and you can not capture it. That's dead algae and you need to SLAM your pool.

That's a pretty big pool and you need a good pump and filter to handle it but I am almost sure yours is a chemistry problem that you need to solve by SLAMming the pool.
 

Fronzizzle

Active member
Jun 29, 2017
34
Augusta Township, Michigan
Thank you for the responses. A few more questions, then:

1) Regarding a robot, my wife and I have been over this many times and while we want one, I'm not sure which is best for an above-ground pool that won't damage anything. Recommendations?

2) I read the SLAM instructions, it says to vacuum the pool every day - do I vacuum it first and then start the SLAM or can I start the SLAM and then vacuum tomorrow?

3) As long as done properly, the SLAM won't hurt anything right? So even if my issue isn't algae I'm fine doing it?
 

gonfishin

Gold Supporter
Jun 13, 2017
330
Rochester, MN
Thank you for the responses. A few more questions, then:

1) Regarding a robot, my wife and I have been over this many times and while we want one, I'm not sure which is best for an above-ground pool that won't damage anything. Recommendations?
Any robot which states it is for a vinyl above ground pool will not damage your pool. However, if you get a robot that is for an in-ground pool you could. I absolutely love my Dolphin.


2) I read the SLAM instructions, it says to vacuum the pool every day - do I vacuum it first and then start the SLAM or can I start the SLAM and then vacuum tomorrow?

3) As long as done properly, the SLAM won't hurt anything right? So even if my issue isn't algae I'm fine doing it?
The more junk that is out of the pool at the start of the SLAM, the better. I would recommend vacuuming first, but you don't have to. SLAM levels of chlorine will not hurt anything.
 

Fronzizzle

Active member
Jun 29, 2017
34
Augusta Township, Michigan
Thanks (again) for the replies. I just tested my pool water, and I have some questions about doing a SLAM.

Apparently, my wife added some chlorine tablets to the pool because our chlorine level is high (for us). When I did the OCLT the other day, I got 7 PPM at night and 6 PPM in the morning. I just checked it at we are now at 14 PPM. My CYA is high, at 70 so according to the chart I should bring the chlorine up to 28 PPM. My pH is good at 7.3.

So, my question is: How do I know when I'm done? The article on slamming lists 3 conditions:

* Pass the OCLT with 1 ppm loss of chlorine, which I already did.
* Have 0.5 ppm or less CC - I'm at 0.
* Have clear water - my water is and has been crystal clear.

So, I have no problem adding liquid chlorine (actually, what I have is liquid shock) but I'm not sure how to tell how long to let it go.
 

Rocco

Well-known member
Dec 23, 2012
227
Manassas Park, VA
Fronzizzle,

Another thing that may be worth trying is to get a bucket, fill it with water, place it next to the pool and see if it also gets dirt on the bottom. This will let you know if something is making its way into the pool or if the dirt is originating from within the pool or equipment.
 
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Casey

TFP Expert
LifeTime Supporter
Apr 16, 2007
10,929
SW PA
Your CYA is high at 70ppm. I would strongly caution you against using chlorine pucks as it will continue to drive your CYA up.

Did you check and see if you could pinch the "dirt" between your fingers or does it poof? If it proofs you need to continue to SLAM until all that junk resolves itself.
 

Poolzzz

Well-known member
Aug 14, 2017
373
Vancouver, BC
What test kit are you using? Are you testing with 10ml sample?

Did you have the tablets in the water when you did the oclt? They need to be removed for an oclt or the results are invalid.

7ppm is low to do an oclt especially with cold water and cya of 70. Even 14 is low for your conditions but do again at your current 14 and see what you get. I suspect you won't pass the oclt.
 

Fronzizzle

Active member
Jun 29, 2017
34
Augusta Township, Michigan
I'm using a Taylor test kit. It's pretty robust and got the best reviews when I was looking - is there something else I should be using?

Yes, using 10 mL.

Yes, I think there were tablets in there - I removed our floating device that administers them, but my wife had put one in the strainer, too.

I tried to scoop out the dirt, but was unable to - as soon as you get close to it, it would mix in with the water and disappear completely...which I'm guessing means it's algae.
 

Fronzizzle

Active member
Jun 29, 2017
34
Augusta Township, Michigan
A quick update, and a couple of questions.

When I first started the SLAM, the pool was disgusting and took me a long time to vacuum. Yesterday, it wasn't nearly as bad and was vacuumed pretty quickly. I checked this morning, there is hardly anything in there. Yay!

At 8:30 PM last night, my FC ppm was 24.5. At 6:30 AM this morning, it was 24.0. Hardly any loss.

My CC is still 0.5 ppm. I actually think it's less but I've been doing the 10 mL sample which isn't as precise.

I think I'm going to continue the SLAM for one more day, then let it go back to normal. Here are my questions:

1) The chlorine/CYA chart on this website says to maintain an FC ppm level of 8-10 ppm. This is significantly higher than the chart that came with my testing kit, but I assume that is because that chart makes no adjustment for CYA level (and mine is high). Is that correct?

2) Two-part question: I've been running my filter for 8-9 hours a day, from 11 am to 7 or 8 PM. Is that enough time or does it need to be increased? My filter is a Hayward S166T92S, which has (according to the info I can find) a 35 gpm flow rate. My pool is approximately 13,340 gallons. And are those good hours to run, or is it better to run earlier in the morning or later into the evening?
 

JoeSelf

Gold Supporter
Jun 18, 2014
601
Glassboro NJ
Slam is complete when your pool is CLEAR, no more stuff on bottom every day, you have passed 2 not 3. keep it going until all three are done. You water should sparkle in the sunlight. POP (pool owner patience) is in order.
 

Fronzizzle

Active member
Jun 29, 2017
34
Augusta Township, Michigan
You water should sparkle in the sunlight. POP (pool owner patience) is in order.
I live in Michigan, so far this year sunlight has just been a rumor. :rolleyes:

Raining/overcast again today. But point taken.

Here are some pictures. In the last one, you can sort of see some small spots of "stuff" on the bottom. And this brings up another issue I have - our vacuum sort of sucks. Well, actually, its more accurate to say it doesn't suck. The skimmer is like 15 years old, the basket broke and we never had the correct vacuum plate. I've cobbled together pieces that I've bought from various locations, but none are the correct ones. I did another deep dive on Google yesterday and found another basket/vacuum plate to try, it should be here Monday - hopefully this one is correct. Anyway, since we've had the pool I don't think we've ever had the bottom 100% clean. I think we are able to vacuum up most of the debris, but the rest just gets stirred up and then gets re-deposited on the bottom.
 

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mjlinss

Gold Supporter
Jun 2, 2017
64
Columbia, MO
I had the same problem with using a manual vacuum. I know my chemistry is good but when I'd vacuum it would kick things up and then about an hour or 2 later it would settle and it would be hard to tell anything was done in the first place. A lot of it was sand (issue with plumbing the filter backwards, my stupid mistake) and some dirt mixed in. I bought a dolphin E10/Active 10 this year and it has worked wonders. I drop it in a few times a week with an additional time thrown in if we are having a group of people over. 2 hours later and there's not a trace of anything on there. It is made for above ground pools due to cord length which is 30 feet so may be a bit small for your pool, but if you have a power source near the middle of one of the sides it would cover it. I have a 24' round and it gets everywhere.
 

Fronzizzle

Active member
Jun 29, 2017
34
Augusta Township, Michigan
Here are more pictures, with the ladder at the bottom. It's windy out so the water is rippling quite a bit, not sure how helpful these will be. I turned the pump off to take them, but it didn't help much.

It's been raining on and off all day, with brief periods of sun but mostly cloudy. I'm not sure what normal chlorine loss is, but I checked mine at 3 PM and it was 21.5 ppm, a drop of 2.5 ppm since 6:30 this morning (8.5 hours).
 

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