Draining and bringing down the waterline?

Ok I haven’t looked at your filter, but generally you just bumped it, you need to perform a full backwash.

what model of filter do you have? This will help us know how much DE you need to recharge after the backwash.
hayward DE Separator, Pentair fns plus fiberglass DE filter - Model FNSP36
You will also need to fully clean the de separator BEFORE you backwash. Then you will clean it again after the backwash.
k how do I clean this? Any direction/video?
To backwash you would move the multiport valve to backwash for approximately 2-3 minutes. If you have a sightglass you backwash until the water runs clear through the sightglass. After the backwash you then move the valve to rinse for about 30 seconds to a minute. Then you will return the the valve to filter mode. Once you are in filter mode you add DE in the skimmer. To know how much DE to add for this we need to know your filter specs. Usually you will add 80% of the clean charge amount for a recharge.
Ohh DE goes to the skimmer, did not know that, I thought it went to the separator or the filter :p . Dang.
A couple of pointers: always turn off the pump when moving the multiport valve. Move the valve the same direction each time (usually counterclockwise). Don’t breathe the dry DE when adding it to the skimmer on the recharge. When recharging, add the DE back a scoop at a time and wait for it to dissolve/dissapear in the skimmer before adding the next scoop. (Do you have a de scoop? It looks like an old style hospital pitcher, or a plastic quart jug with a handle And will have a line or markings that tell you where 1 pound is on the container.)
I don't have anything like this, though I do have a bag of DE.
 
Here’s your filter manual:

Your clean charge amount is 3.6 pounds of DE. On a recharge you would add 80% of that amount or 2.88 pounds….just round it up to 3.

To clean the separator you open the top and the used DE will be contained in a mesh bag. Clean out the bag in the trash, rinse and reinstall the bag.

If you don’t have a DE scoop you can weigh it out, but a scoop will be way less messy.

Hayward EC10SC50 Pre Measured DE Scoop, 1-Pound https://a.co/d/bVxrqe7
 
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Ohh DE goes to the skimmer, did not know that, I thought it went to the separator or the filter :p . Dang.
The only time DE enters the separator is when you backwash, rinse or waste. Because your system recycles the water back in the pool, its job is to catch the used DE.
 
@Lake Placid - Sort of a related question, can I use perlite (aqua perl) instead of DE? I was thinking of using this from next time onwards anyways, if I'm going to clean, might be a good time?
I don’t have any personal experience with it. It seems from the forum that some users experience faster than normal pressure rise with it necessitating more backwashes. I personally don’t mind handling DE and get good performance from it, so I wouldn’t switch. If you do go that direction, I’d suggest lots of researching here before you do.
 
Yes you only need to clean the separation tank. The backwash will clean the filter. If I recall correctly you’ve never cleaned the separator and based on our previous experience it’s full. That’s why I said to clean before you backwash and after. Going forward if you start with an empty tank, you only clean it after the BW cycle.

The time you need to open the filter for a deep clean is about once a year. I usually do a deep clean as a part of my winterizing process, so each season I’m starting with a fully cleaned filter. Since it’s new to you you could open the filter and fully deep clean it, but thats a little more time based on disassembling the filter. It’s not necessary now but you definitely will want to do it at some point in the future.
 
@Lake Placid - just so that I understand, why do we need to clean the separation tank after each backwash? Mostly I wanted to understand the mechanics. Unfortunately, I don't see a lot of youtube videos showing cleaning of separation tanks, even though I've found quite a few filter related videos for cleaning DE filters themselves.

The pool pressure is low and steady as of now, I was hoping to have the pool professionally closed next month. Would it be ok to wait and have them clean it? I can probably have a look as to how they go about doing it, instead of doing it the first time myself.
 
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Ok let’s start with a very basic theory of operation of the DE filter. You have the filter tank and inside the tank, it has vertical pipes that are covered by mesh grids. When you add DE it surrounds the mesh grids to filter the debris out of the water and the mesh grid doesn‘t allow the DE to get into the vertical pipes and back into your returns going to the pool.

In normal filter operation dirty pool water water enters the tank on the outside of the grids. The water then moves through the DE, through the mesh grids and into the vertical pipes, then the clean water moves out of the filter and back to the pool. Obviously in this process the DE and grids get clogged with dirt. Over time as you have experienced this dirt will plug your filter and slow flow of water back to the pool, necessitating a cleaning of the filter.

To clean the filter we backwash it. This process reverses the flow of the water through the filter. So now the water enters from the pump through the vertical pipes, flows backwards through the mesh grids loosening the DE and dirt, and then moves up and out of the filter through the waste pipe. When this water leaves the filter it carries both the trapped dirt, but all the DE with it as well. In some setups the waste pipe runs to daylight in a yard, storm sewer etc. In your setup, your waste pipe returns to the pool to not lose the water. This is where the separation tank comes into play. In your setup all the spent DE and dirt moves from the filter through the waste pipe and to the separation tank where the DE and dirt is trapped by a mesh bag for disposal before the water travels back to the pool.

Obviously, each time you backwash, the separation tank will fill with DE and dirt. This has to be removed before you backwash again as the system is full. You need the space for the new load of DE and dirt. If you don’t clean the tank, you risk overpressurizing the tank and destroying components when more DE is packed into it during a backwash cycle.

If you don’t backwash, your filter will continue to clog with dirt, you will lose flow, not be able to generate chlorine, not filter the water, could damage your pump, overpressure your filter and blow it up, etc etc etc.….lots of bad things could happen.

Based on your flow sensor tripping out, you know the filter is packed full enough to impede flow. You went from a dirty pressure of 28 down to a clean pressure of 13 after you bumped it. Most manufacturers tell you to backwash at max a 10 psi rise over clean pressure. Trouble free method is 25% over your clean pressure or about 16-17 psi. You need to backwash, it’s routine maintenance. Unfortunately it can’t wait a month, and you’re going to have to work through cleaning the separation tank to be able to do it. The filter is going to keep plugging and flow slowing until you backwash it.

You can do it. You changed out the flow switch, you can do this. Give yourself plenty of time and don’t rush. Read the 8 cleaning instructions on page 1. Look at the parts diagram on page 2 to get familiar with the separation tanks components. Reread both. Ask questions here. It‘s straightforward and not nearly as involved as deep cleaning a filter like you’ve seen on video. Don’t let it intimidate you.

That said, if you wanted to have the tech show you how to deep clean the filter, that can absolutely wait until you get them out to close the pool for you.
 
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@Lake Placid - I was able to clean the separation tank. Was surprisingly easy, so glad I did it. A few follow up questions

1. Why do we "RINSE" after backwash?
2. The amount of DE in the separation tank was really little (i.e. there was a coating of DE on the bag, and there was some DE at the bottom, but largely the bag was empty), is that expected?
3. What specifically am I supposed to see in the glass on the multi-port while backwashing? Like swirling particulates? dirt? For the most of it the water in the glass on the multiport appeared clear. Although I did initially see some white particulates, but they disappeared in like 5 seconds
4. More of an fyi, but I also bought the DE mug as suggested, so technically now have a measuring cup. :)
 
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@Lake Placid - I was able to clean the separation tank. Was surprisingly easy, so glad I did it. A few follow up questions

1. Why do we "RINSE" after backwash?
The rinse setting on the multiport valve flows water back in the normal direction (just like in filter mode) but flushes the wastewater out the waste pipe. This flushes any remnants of DE out of the filter circuit out of the system instead of back into your pool.

@Lake Placid - I was able to clean the separation tank. Was surprisingly easy, so glad I did it. A few follow up questions

2. The amount of DE in the separation tank was really little (i.e. there was a coating of DE on the bag, and there was some DE at the bottom, but largely the bag was empty), is that expected?
This is surprising. Do you think the amount in the bag was close to the amount of DE used to recharge the filter (3 pounds or so?)

@Lake Placid - I was able to clean the separation tank. Was surprisingly easy, so glad I did it. A few follow up questions

3. What specifically am I supposed to see in the glass on the multi-port while backwashing? Like swirling particulates? dirt? For the most of it the water in the glass on the multiport appeared clear. Although I did initially see some white particulates, but they disappeared in like 5 seconds
When looking at the sightlglass when backwashing you should see dirty water first, then milky color, then clear. This is the dirt passing out the waste pipe first, then DE. It should look very sludgy and full of sediment. Eventually you just see clear water as the filter is empty. If a grain or two of DE is in the sight-glass that’s ok, but it should be clear before switching to rinse. The length of time it remains dirty while flushing will vary based on the amount of dirt and volume DE in any given filter.

Nice job on getting it done, it really is easy 😁. Did you have any difficulty recharging the filter with DE when you finished?
 
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Did you note the working pressure after you recharged? This is the baseline clean pressure you use to judge when it’s time to backwash based on the future pressure increases.
 
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@Lake Placid

Thanks for your words of encouragement. They def helped :)

This is surprising. Do you think the amount in the bag was close to the amount of DE used to recharge the filter (3 pounds or so?)

Probably both the initial clean and then the second backwash combined could possibly have 3lb. It's difficult to tell, the bag partially had water. Another thing was I don't think there was a lot of dirt. Given the algae bloom earlier, I was expecting at least some dirt, but this largely looked like white DE. Finally another confusion was that you had mentioned to empty it into a bag, but it was all wet, the only option seemed to rinse the whole thing out.

Did you note the working pressure after you recharged? This is the baseline clean pressure you use to judge when it’s time to backwash based on the future pressure increases.

Yes it was around 11/12
 
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