How much de powder do I need?

[sdtfp]

Opening pool myself this year and want to know how much de powder to buy. I look at the filter and the labels seem to be worn out. The filter was cleaned last season so I need a full amount of de powder.
I'm liking it up and it looks like it's based on filter sq in. But my filter is round and 3 dimensional so I'm confused what's the math for sq in?

On the phone with the label all I can see is what I think says "pyrex triton fns plus"

The outlet label on the attached picture says "label 98739300" in case that help narrow it down. Interesting that label is perfectly fine but the label with the size information seems to be totally wasted away.

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After doing some more research I found an article detailing how to measure the filters.. I measured 30 inches tall. I am not sure how to do the two measurements for the width. The article i raid said 11.5 and 9.5 and I think I have the same results but I maybe measuring the wrong thing.

Also I couldn't take out the filter as the screws? on the top do not budge. What kind of tool do I need for that? Looks like its for hand grip, but my hand grip is not budging it. Any tricks to it?

 

[Rancho Cost-a-Lotta]

If you don't get an answer, you may need to measure the length of the grids and do some research from there. Here's an example: a 60 sq./ft. filter uses this 30" grid.

 

[sdtfp]

If you don't get an answer, you may need to measure the length of the grids and do some research from there. Here's an example: a 60 sq./ft. filter uses this 30" grid.

I called pentair and they said to measure the filter housing.. i did and they said its a 48 sqft filter.. Then I told them I think the filter grids are 30" in length and so they said then its a 60 sq ft. So yeah Im still confused, but leaning towards 60 since im pretty sure the filter is 30" tall, I just need to budge it out to confirm. But at least for now, I know that if I buy 6 lbs of de powder I will be covered in both cases. So I'll buy the powder, and work on getting the hand nuts untightened when I get some more time.

 

[Candurin]

If it is 60, then you would use 6 lbs of DE (taken from pentair manual). Rule of thumb is 0.1 lbs/sq ft of filter surface area.

 

[sdtfp]

Last year was first year with pool and this year will be first year I do everything myself. I did a lot of testing last year and my CYA was always 130+. This is with tfkits and leslies pool store. After much research I decided this spring I would drain 3/4 of the water and refill. Last week I was getting some supplies, so i Had the water tested at leslies. CYA was 54. I was shocked, but wanted to confirm with my own test. This week I got around to it and the CYA was on the 50 line , maybe you guys would say 60 as I know some of you guys are conservative about it.
So now, what do I do? Do I believe that the CYA just disappeared over the winter or am I missing something. I had the pool guys close the pool and they put in some chemicals. Could any of those reduce CYA and what would do that? I have to figure this out soon because I think I need to open soon and I want to do the water drain before that.

Also, I have 0 chlorine in the pool right now, since I was worried about the CYA and did not put any tabs over the winter. The water looks fine right now, but I measured the water temp with an infrared shopw thermometer and it's now 65 degrees. Not the ones u would use on people, but the one you would use to find drafts in a house. I'm guessing it's great at gettign the temp, but I feel it gives a good ballpark. In any case, how do I determine if I should be opening the pool right now so that it doesn't turn green with algea? Or since my CYA since to be down, should I put in a floater with a tab? Around here, i think people open after the second week of may, but I assume that is with chlorine from the floater tabs. So I'm kind of panicking wondering if I should be opening the pool or not.

 

[kellyfair]

If your CYA is at 50 or 60, why would you want to raise it? You don’t have a SWCG, correct?

 

[ajw22]

CYA 60 is fine in the NYC area for a SWG or liquid chlorine.

I opened my pool 2 weeks ago.

My water temperature is about 61 degrees. You just measured the surface water temperature. Your pool is colder than 65 degrees with your water not being mixed without your pump running.

It is time to open your pool, get the pump running, and get chlorine in the water.

 

[sdtfp]

If your CYA is at 50 or 60, why would you want to raise it? You don’t have a SWCG, correct?

No I don't have salt water pool. I definitely do no want to raise cya. I was planning to replenish 3/4 of the water. Do you mean raising it by putting in tabs?

CYA 60 is fine in the NYC area for a SWG or liquid chlorine.

I opened my pool 2 weeks ago.

My water temperature is about 61 degrees. You just measured the surface water temperature. Your pool is colder than 65 degrees with your water not being mixed without your pump running.

It is time to open your pool, get the pump running, and get chlorine in the water.

Oh wow 2 weeks ago! Maybe people on the chlorine tabs over the winter get to open it a little later and since I'm going liquid chlorine then I need to open sooner? Or this just variable based on how cold the winter is or how long it lasts?

Do you use chlorine pucks over the winter? I'm now reading that it is possible to lose CYA over the winter here in the NE. I didnt know that before, maybe because most comments on CYA are from pool owners in the south so they dont have that happen. So now, I got to think about how to deal with large CYA loss next winter. Maybe just let it happen and see how much it drops.

 

[sdtfp]

The closer of the pool removed the pump and I stored it in the garage. Do I need to put the pump back on the plumbing before or after I pull the plugs in the pool? I figure it does not matter since the water is lower than the pump in the ground so gravity should keep it down.

Secondly, do I use the pool robot before removing the plugs or after? I don't want large debris in the lines before the pool robot does its work, but the robot may have trouble with the plugs when climbing the walls. I'll definetly manually skim before doing either. And also, should I turn on the pump before or after the robot? I'm pretty sure it's after, but I've seen several opening videos and they turn on the pump right away even with the water all green. But the videos dont have robots! The pool techs had their own pump cleaner so when they opened it, the pump was not started until the debris was mostly pumped out.

The DE filter was cleaned on closing but I noticed a little bit of debris in there when I took a look recently. Should that perfectly clean or since its porbably like 95% clean, I shouldnt worry about it since its self cleaning? I'd rather not clean it just now since its a huge thing and don't want to pull it out.

Do I need to backwash at all? I saw a video opening to waste and one to filter, so Im not sure what the purpose of opening to waste is? I have a backwash tub (is that what its called) connected to my filter but I've never used it. Is that where waste line goes or is waste line to the outlet at the bottom of the filter? So basically opening to waste would flood the floor? Also I don't want to use the backwash tub because I forgot to buy a backwash hose, so that would flood the floor as well. I think the purpose of that is to catch the DE and since there is no DE in the system, that doesn't seem very useful for opening.

After opening, right before sunset I will start the liquid chlorine SLAM. Ill let the pump run for 30 minutes and then take a chlorine measurement. Then early morning, before sunrise, I will take another chlorine measure. If at that point, I've lost less than 1 ppm overnight, CC is < .5 and its clear then I know the shock is done and pool is good to go? The pool techs take two weeks to open, and I am confused if it should take that long or if they are just overly conservative. I'm not planning to use the pool any time soon since its cold, but I read you should keep the pump going a lot during opening, so I want to know when SLAM is done so I can go back to a normal pump schedule. Come to think of it, how long should I be running the pump during the opening phase?

 

[sdtfp]

OK so I completed the opening today and started slamming.

One thing that was concerning is that I didnt see air bubbles when removing the plugs on the returns. One plug has a plastic wingnut and that fell apart when I first tried to open it. These plugs look very old. So I guess I'll find out if the lines froze/cracked over the winter by watching the water line and seeing how much water escapes in a week. The overnight temps are around 55 and highs are 70s in the day so I think that means a lot of water should evaporate? I forgot to look at the main drain for air bubbles, so don't know if that one is okay or not.

I thought opening was oging to be easy but it was quite a challenge. I had the active 20 on cleaning up the dirt and worms in the pool and that had to be emptied like every 20 minutes. After like 4 hours, it's still a bit dirty in the bottom.

I started the slam as planned in my previous but my math seems to be off. I used the pool math calculator. 18k gallon pool, CYA 50 and FC of 0 and wanted to get to 20-24 FC from 0. Calculator told me 3.4 gallons of 12.5% (128 oz) trade bleach and so I put in 4 gallons since I couldn't be bother to measure out 2 quarts. I let the pump run for about an hour and the FC came back at 39.5. Yes that is a lot of drops!!! I got the gallons of super shock from leslies pools and it says 12.8% and 1 gallon. So I am not sure how I messed that up. Maybe the pump needs to run more? I poured it in by gettign a 5 gallon home depot bucket, filling it with pool water, adding 1 gallon of chlorine and then spreading it around the pool. I did this 4 times. Anything to worry about for such a high FC? CC was 1.0.

I turned off the pump over night. As I asked in previous post, not sure if its a hard requirement to keep that on 24/7 when slamming. It'll turn on in the morning.

I'm also wondering if I should do a chlorine test tomorrow morning. I'm pretty sure the slam won't be done since the water was cloudy green. I forgot to mention that before. After removing the cover, the water seems normal except for the dirt at the bottom. The active 20 stirred that all up and the water turned cloudy green. So I doubt that will be gone in the morning, so no need for an overnight test tomorrow. I'll do one at night to confirm FC is still above 24. I don't need to keep adding chlorine unless it goes below 24 correct? Overdoing it to 39.5 seems to have the benefit that its less likely I will need to add more chlorine for a day or two. But I've never done a slamm on a green pool, so maybe I will be surprised how much chlorine is gone in one day.

 

[mguzzy]

In the early days of a SLAM Process you want to test frequently to keep your FC at your target. If there is a lot of algae it can consume it quite rapidly. You would be amazed. As to your CYA.. yes it can degrade over the winter by a number of mechanisms. So check your values at the beginning of the season and adjust accordingly. Some people will use a combination of pucks and liquid chlorine to manage their CYA. But many just save the pucks for when they go out of town.

I use a leaf rake to scoop out as much big crud off the bottom of the pool as I can and I leave the little stuff for the pool sweep. Worms would qualify as big crud in my book.

This is your first opening on your own? Sounds like it is going well! It will get easier the next time.

 

[sdtfp]

The pool is clear now and im keeping the FC over 24. Now I noticed the pressure gauge went up to 23. IT was 14 yesterday. Is it normal for 1 day of slam to make psi go up so much? It's a small pool and i didnt think it was that green. But I did have a lot of dirt from the earthworms. So I guess I should backwash now just to be safe and refill the DE? I put in 6 lbs DE in my 60 sqft DE filter. If i backwash it 3 times as ive seen on videos, should I refill with 6 lbs of DE or do I need to do less? And how to calculate how much less?

 

[mknauss]

When your filter pressure rises by 25% over clean pressure, you need to backwash/clean your filter.

Your filter documentation should tell you how much DE to add after a backwash versus a full cleaning.

DE filters are great at cleaning the pool water, but plug quickly during a SLAM.

 

[sdtfp]

When your filter pressure rises by 25% over clean pressure, you need to backwash/clean your filter.

Your filter documentation should tell you how much DE to add after a backwash versus a full cleaning.

DE filters are great at cleaning the pool water, but plug quickly during a SLAM.

Thanks thats good to know that slamming will require a backwash. I wasnt expecting that.

I'm still uncomfortable about the amount of DE in my filter since I don't have the manual. It's an old purex fnsplus 60 sqft. Now that line is owned by pentair, but I am not sure if the specs of the new ones would match my old one. I found this sku-page and https://images.inyopools.com/cloud/documents/pentair-filters-fns-plus.pdf.

I don't see it mentioning the DE refill amount after backwash, so I assume its the full amount. Just to double check my understanding, manual says 12x1 lbs coffe can of DE for 60 sq feet. But the scoop (1 lb Diatomaceous Earth DE Powder Scoop | Leslie's Pool Supplies) I got at the pool store says its for 1 lb of DE, which I think the guy or the bag mentioned is for 10 sq feet. But now I am reading (Leslies DE scoop weight) and it seems I should count it as .7, so I need 8.5 scoops? I only put 6 scoops so I guess I might have put too little to begin with. But the manual says 12x1 so does that mean I need 17 scoops?

 

[mknauss]

FNS Plus manual.

 

[mknauss]

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