SLAMing with a DE filter - when/how often to backwash and clean filter grids?

[jersey]

My pool is currently a green cloudy mess that appears to be getting worse. It's 16x32 and I can't see to the bottom even on the shallow end. After years of struggling to fight off algae by making tons of trips to the pool store with no help, I found this site and I hope to take control of the problem myself this year.

I'd like to start to SLAM the pool, and I now understand I need to measure CYA and FC and bring FC to a certain level according to the chart for several days and I'll have a clean pool.

The pressure on my filter tends to rise from 22 to 30 every few hours. I backwash, rinse, repeat, and am able to get it down to 22 temporarily. I have a DE filter and I've been using "Pro Guard" cellulose fiber instead of DE (they claim it works better...not sure if this is true). So I assume I'm supposed to add more cellulose fiber/DE every few hours after I backwash the filter? This seems like a very expensive thing to do.

My questions are:

1. When/how often should I clean the DE filter grids completely (i.e., drain the filter and hose off everything)? Should I do it before SLAM? After SLAM? Before and after SLAM? At the end of the year?

2. When my filter pressure raises from 22 to 30 every few hours, does that require me to backwash it every time? If so, am I supposed to be adding cellulose fiber/DE every few hours?


I intend to order a Taylor K-2006 test kit to start he SLAM process, but unfortunately I've called 5 pool stores and none of them have it in stock. I'm going to order it on Amazon unless I can find it tonight. If anyone knows of any chain/brick and mortar shops that carry the test kit that would be helpful as well. Thank you all!!!

 

[Richard320]

Welcome!

You understand correctly. That ii the downfall of a DE filter -- they filter really well and require recharging after every backwash. It never washes off 100%, so only use 80% after a backwash. 100% if you break it down for a thorough cleaning. Don't be tempted to run without adding DE or cellulose. You'll wreck the grids.

If your filter has a multiport valve you can run things on recirculate for a few days, and then vacuum to waste and get all the settled crud out without overloading the filter. If it turns out CYA is really high, that is also a good way to replace water. If you have a slide valve or an internal backwash, you're out of luck.

Deep cleaning? For sure when the water starts just looking hazy. You might have to do it sooner if you're backwashing every couple hours because the cellulose can get sticky and may not flush off completely.

Just keep in mind that this could well be the last time you have to deal with a swamp in the spring.

 

[jersey]

Thank you so much Richard! This is very helpful! I hope you are right, I want to get rid of the swamp for good.

My filter does have a multiport valve. So I'm going to take your advice and run things on recirculate for a few days because when I'm at work, I really can't get to it to backwash as often as it needs. I'll vacuum to waste and replace the water.

Because I likely won't have the proper testing kit until next week, I'm just going to go to the Leslie's pools now and have them test the water for me. I understand that depending on the person completing the test these results can be inaccurate, but it's what I have for the time being.

For the first time in years I am optimistic I can get this under control. Thank you for your help!

 

[jersey]

0 FC in the AM?

I'm in trouble. Is it possible for your pool to drop more than 5 FC overnight? I put 8 bags of 1lb shock and 5 gallons of 10% chlorine in the pool yesterday and the chlorine level in the pool this morning at 10AM was 0. I have a D.E. filter and have been running it on recirculate so that it doesn't constantly clog the filter every 20 minutes and require backwashing and recharging with DE.

My pool is 23k gallons of a green mess (I can't see to the bottom) with a vinyl liner.

I would like to do the SLAM method but am forced to rely on pool store test results until my K-2006 kit arrives next Wednesday. I bought a Leslie's DPD test kit as a stopgap measure.

The pool store may be giving me inconsistent results...

Here are the pool store readings yesterday:

Day 1:
FC = 0.5
CYA = 40
pH = 7
Total Available Chlorine= 0.5
Alkalinity = 30
Base Demand = 2

They told me to add 1lb of Soda Ash. Then 3 lbs of "Green to Clean." Then 2, 1lb bags of shock every 12 hours. So I did the following:

I added 1.5 lbs of soda ash and waited 2 hours and tested the pH, which seemed to be about 7.5. I added 2 1lb bags of granular shock. At the 4 hour mark I added 4 lbs of this Green to Clean stuff, waited 5 minutes, then I added 3 1lb bags of granular shock and then 1 gallon of 10% liquid chlorine. The maximum this DPD test shows is 5 FC, and I was consistently reading a 5 FC at this point and the rest of the day.

I did the same 3 hours later (3 1lb bags of shock, 1 gallon of 10%). 4 hours after that, at 10PM I added 3 gallons of 10% liquid chlorine (according to pool math that is enough to bring the pool up to a 16 FC from a 5). I was worried I was raising my FC level too high and may be bleaching the liner, but I wanted to do what I could to get the chlorine up to SLAM level, which was 16 for my pool with a CYA of 40.

So in total, I added 8 1lb bags of granular shock and 5 gallons of 10% liquid chlorine in a 12 hour period between 10AM - 10PM.

So the next morning I wake up...still totally green. I take a water sample at 10AM and go to the pool store to test the water. Here are the results:

Day 2:
FC = 0
CYA = 60
pH = 7
Total Available Chlorine= 2
Alkalinity = 40
Base Demand = 5

I went and tested the water myself with the DPD kit and sure enough, the chlorine dropped to 0 overnight. Now, with a CYA level of 60, my pool needs to get up to a 24 FC for slam level. According to pool math, to get from 0 to 24, that's 5.5 gallons of 10% liquid chlorine.

Could the pool store's test results be accurate? If so, should I add 5.5 gallons of 10% chlorine into the pool and keep going back to the pool store every few hours? I'm afraid of wasting a whole bunch more of chlorine.

I would greatly appreciate anyone's help. Thank you so much!!!

 

[tim5055]

Re: 0 FC in the AM?

WhT you need to do is SLAM Process the pool. Yes, if it is a green mess then the chlorine is being consumed as it tries to clear the water.

You need your own test kit and to stop going to the pool store.

You also need to stop,using those bags of shock. They are almost half CYA, so every bag you add is driving up your CYA.

ABCs of Pool Water Chemistry

At this point if your CYA is actually 60 (I'm guessing it's actually higher from all the bags of shock) it will be next to impossible to clear the pool due to high CYA.

You are making it even worse by adding the green to clean. That is an ammonia based product that creates a huge chlorine demand.

To be blunt, are you going to follow our procedures or the pool store? Trying to do both is just making things worse.

 

[Texas Splash]

Re: 0 FC in the AM?

I'm in trouble. Is it possible for your pool to drop more than 5 FC overnight?

Yes, because of that algae. It can be quite aggressive. You have the right test kit coming, so you'll have to be patient. You can run your filter on recirculate if you have a multiport. If you're stuck with a plunger valve, then you have to clean it often. Just hang tight. No guesswork, no wasted money. The DPD won't give you the accuracy you need, so don't bother right now. When your kit arrives, test/adjust ph to 7.2, confirm CYA and FC levels, and we'll go from there. For now, just add one gallon of regular bleach to your pool and sweep/brush to stir things up. The real work begins when your kit arrives.

 

[jersey]

Re: 0 FC in the AM?

Thanks Tim! I do know about the SLAM method, but wanted to rely on the pool store to complete SLAM until my test kit came in. Was just wondering if the pool store test results seemed consistent. But you are right, I should probably just deal with a green pool for now and just wait until my test kit comes in next Wedesday.

Pool store said I have a "chlorine block"...is that a made-up thing to get me to buy more of their products? Or is that a real thing?

- - - Updated - - -

Thanks Texas Splash! OK sounds good, I will need to be patient. Ugh what a waste yesterday was. Lesson learned! I'll wait for the test kit to come in.

 

[tim5055]

Re: 0 FC in the AM?

Thanks Tim! I do know about the SLAM method, but wanted to rely on the pool store to complete SLAM until my test kit came in. Was just wondering if the pool store test results seemed consistent. But you are right, I should probably just deal with a green pool for now and just wait until my test kit comes in next Wedesday.

Pool store said I have a "chlorine block"...is that a made-up thing to get me to buy more of their products? Or is that a real thing?

- - - Updated - - -

Thanks Texas Splash! OK sounds good, I will need to be patient. Ugh what a waste yesterday was. Lesson learned! I'll wait for the test kit to come in.

You can't SLAM Process with pool store testing. A SLAM Process requires testing ever hour or two.

Chlorine "lock" is made up by the pool stores because they don't understand what CYA does to the ability of chlorine to work.

You need to prepare yourself to replace about 50% of your pool water because,of pucks and/or granular chlorine.

 

[jersey]

Re: 0 FC in the AM?

Ah gotcha. The chlorine lock is a myth. I am so glad I found this site! I regret spending so much money at the pool stores in the past but man I'm lucky I stumbled here.

I wish the pool stores carried the K-2006 kit, but maybe they would lose money if they did. I have the time this weekend to work on the pool, but during the week I'm not going to be able to check the pool from about 9AM - 8PM. I hope I can work around it somehow by doing most of the work on the weekend.

 

[tim5055]

Re: 0 FC in the AM?

Ah gotcha. The chlorine lock is a myth. I am so glad I found this site! I regret spending so much money at the pool stores in the past but man I'm lucky I stumbled here.

I wish the pool stores carried the K-2006 kit, but maybe they would lose money if they did. I have the time this weekend to work on the pool, but during the week I'm not going to be able to check the pool from about 9AM - 8PM. I hope I can work around it somehow by doing most of the work on the weekend.

While,the SLAM Process works best if you hit it hard, fast and often, it can be done with a work schedule. You test and adjust to shock level before you go to work, as soon as you get home from work and just before bed. That is your 3 times a day. Once the weekend hits you go into overdrive and test and adjust every hour or two.

Remember, the K-2006 is the small kit, the the K-2006-C is the larger kit. But, the TF-100 with the XL option is what you want for a big SLAM Process. Without the XL option all of the kits will run out of reagents in the middle of the SLAM Process.

 

[jersey]

Re: 0 FC in the AM?

My K-2006 arrived today, 4 days early! I'll SLAM the pool tonight and hope to have some updates tomorrow. Thank you so much everyone!!!

 

[tim5055]

Re: 0 FC in the AM?

My K-2006 arrived today, 4 days early! I'll SLAM the pool tonight and hope to have some updates tomorrow. Thank you so much everyone!!!

Remember, the SLAM Process once started is a process, not a single event. The key facotor is to maintain the shock level as best you can during the SLAM Process.

I'm serious, if you got the K-2006 you will use the FAS/DPD chlorine test reagents quickly. You may want to order more now. The worst thing is to get five or six days into a SLAM Process and run out of testing supplies.

 

[jersey]

Re: 0 FC in the AM?

Oh ok wow, I had no idea the reagents would run out so quickly. Which ones should I re-order? Should I re-order the R-0870 DPD powder and the R-0871 FAS-DPD Titrating Reagent?

 

[tim5055]

Re: 0 FC in the AM?

Oh ok wow, I had no idea the reagents would run out so quickly. Which ones should I re-order? Should I re-order the R-0870 DPD powder and the R-0871 FAS-DPD Titrating Reagent?

Yes, those are the ones

 

[jersey]

Re: 0 FC in the AM?

Thanks Tim, I reordered those. I didn't realize how many drops I would need.

First readings were:

CYA: 60
FC: 0

According to the chart, FC target should be 24.

I started the SLAM process tonight. I added 6 gallons of 10% liquid chlorine. I waited 1 hour and got an FC of 25.

Tested again in 90 minutes, FC dropped to 21. I added another gallon of 10% liquid chlorine.

Went to sleep, tested 6 hours later. FC dropped to 18. Added 2 gallons of 10% chlorine to bring levels back up to SLAM.

My question is - during the SLAM process, is it acceptable if FC drops below of SLAM level as long as you bring it back up to SLAM levels within a few hours? Or is it necessary to bring the FC way above SLAM level to compensate for this anticipated drop in FC? Thank you! Also, FYI, here is a current picture of my pool (very green and swampy):

 

[tim5055]

The goal,is to keep it at slam level as much as possible. It,is understood that life gets in the way and at times it will drop, but as soon as possible,bring it back up.

 

[jersey]

OK, took a second reading today, 1 hour after adding the 2 gallons of 10% chlorine.

8:40 AM is FC 25. I'll keep checking throughout the day. I think I'm going to wind up buying all of the bleach/chlorinating liquid from all of the Walmart stores in the area.

Though I am running my filter on recirculate, I would also like to clean the DE filter grids at some point to get the filter ready for action when the water turns cloudy blue.

Can I take the filter off recirculate for a few hours while I clean the filter grids? Or does the pump need to be running 24/7 without interruption during the entire SLAM process?

11:40AM FC dropped to 19. Added 1.4 gallons of 10% to bring back up to SLAM.

Added .6 gallon 10% at 1:30 and 1 gallon at 3PM.

4PM FC measures 25. Still in SLAM range.

Added 2 gallons of 10% arond 6PM.

8:50PM FC is 27

11PM FC is 25, will be pouring rain all night. Added 1 gallon of 10% liquid chlorine going to sleep.

DAY 2

Pool appearance: No huge improvement from Day 1, still cloudy green. Will be able to check FC regularly today, but back to work tomorrow.

10:45AM FC is 22, added 2 gallons of 10%. Very overcast day, which I think is a blessing. Rain has stopped and reports say no more rain today.

2:30PM FC is 25. Upon close inspection the pool does look a lighter shade of green today. I think we're making progress.

Added 1 gallon of 10% chlorine.

10:30PM FC is 29. I'm going to back off adding as much chlorine. The FC level seems to have stabilized. The fact that today was cloudy all day probably helped. I'll check again in the AM. On to Day 3.

 

[Richard320]

OK, took a second reading today, 1 hour after adding the 2 gallons of 10% chlorine. Reading at 8:40 AM is FC 25. I'll keep checking throughout the day. I think I'm going to wind up buying all of the bleach/chlorinating liquid from all of the Walmart stores in the area.

Though I am running my filter on recirculate, I would also like to clean the DE filter grids at some point to get the filter ready for action when the water turns cloudy blue.

Can I take the filter off recirculate for a few hours while I clean the filter grids? Or does the pump need to be running 24/7 without interruption during the entire SLAM process?

Yes. you can shut it off for safety's sake. In fact you should. Sometimes people without recirculate options have to shut it off while they are asleep or at work.

 

[jersey]

Re: 0 FC in the AM?

if you got the K-2006 you will use the FAS/DPD chlorine test reagents quickly. You may want to order more now. The worst thing is to get five or six days into a SLAM Process and run out of testing supplies.

Thank you Tim for this advice! I ran out of the R-0871 FAS-DPD Titrating Reagent, just 48 hours after starting the SLAM process. I would be out of luck tomorrow if I didn't re-order. Thanks for the help!

 

[jersey]

Day 3

9:30AM FC is 25. Lost about 4 over the last 11 hours, seems better than Day 1. Thinking about adding 1 gallon of 10% to cover me while I'm at work.

I have been running the filter on recirculate for the first 3 days. There was a slight improvement in color from a dark green to a lighter green from Day 1 to Day 2, but everything looks about the same on Day 3.



I haven't been running the DE filter on "filter" because I don't want to have to recharge the filter every 30 minutes. My plan is to wait until it turns cloudy blue and turn the filter on at that point. Is that a sound strategy? Or should I be filtering it on a regular basis anyway even at this "green" stage? I'm only able to brush, not vacuum, at this stage because while I've picked up as many leaves as I can with a leaf rake, I know there must be some stray ones down there and I don't want to suck them into the pipes. Am I going to have to vacuum blind at some point during this process? I normally put the vacuum hose right into the hole in the skimmer and bypass the skimmer basket. I do have a vacuum plate like the one pictured below, but when I use that I lose suction every few minutes and the suction I do get is very weak compared with when I put the hose directly into the hole. So I like to vacuum typically only when there are no leaves on the floor of the pool. Am I going to have to find a way to vacuum blind now?



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