Sand filter deep clean and partial sand replacement?

[BrianR170]

I was planning to replace my sand this weekend when I decided to check here and found the thread on deep cleaning sand filter media. I have a Sta-Rite HRPB30 which is a 30-inch diameter filter with 400 lbs of sand. The last time I changed the sand in the filter was 12 years ago and the sand was 12 years old at the time. It was the original sand from the pool builder and I am the original owner of the pool. I knew the stuff about the sand "wearing out" was BS, however, everybody said I should've changed it already. When I changed the sand, what I found made me think changing it was a good idea. Basically, the outer layer of sand that touched the filter housing was a clay-like mud. It was nearly 3 inches thick at the top and only 1-inch thick nearer to the bottom. The rest of the sand looked normal and clean.

The same amount of time has passed, so I'm expecting the same layer of mud around the outside when I open it up again this weekend. However, after reading about deep cleaning, here's what I'm thinking of doing:

Scoop out all of the "clean" sand in the middle and save it.
Scoop out all of the "mud" around the edge and throw it away.
Deep-clean the sand I saved and put it back into the filter.
Add new sand to bring the media level up to where it's suppose to be.

Is this a reasonable plan? Based on what I remember, deep-cleaning the mud wouldn't be practical.

So, now I'm also wondering if I'm maintaining my filter correctly. My minimum filter pressure is 12psi right after backwashing. I backwash for 2-3 minutes when the pressure reaches 15-17psi. I also do what I thought was a deep cleaning by backwashing for 30 minutes once every 2 years. My backwash valve has only two positions; there's no rinse or bypass. I am I doing something wrong? Is the mud buildup a deficiency in my equipment? Would deep cleaning the sand every 4 or 5 years prevent the mud buildup?

Here's a photo of that outer layer of mud. I scraped down a couple inches so you can see the defining light/dark line between the normal sand and the muddy sand.
https://photos.app.goo.gl/TEXvuiNjJwmhNpNR2

 

[mknauss]

I do not own a sand filter but those that do on the forum tend to say a deep cleaning should be done once a year.

Your backwash procedure sounds correct.

Take care.

 

[YippeeSkippy]

Brian, if you can get the top off the sand filter (that multiport valve usually) and lift off any surface schmutz then put a hose in the sand gently down in the sand (so as not to go so far in and disrupt a lateral) you can turn the water on and let the gunk float up and out of the top. Keep that up until the water runs clean.

You need to backwash when your gauge rises 20% over *clean filter pressure*. That may or may not be the 15-17psi you currently use as your mark. Once you clean your filter (and replace any missing sand needed) make note of your clean pressure reading for reference.

You sand is millions of years older than just the 12 years you've had it. Let it work for a few hundred more,'k?

Maddie

 

[BrianR170]

I do not own a sand filter but those that do on the forum tend to say a deep cleaning should be done once a year.

Wow, once a year would be a huge chore. This filter has thirty-two(!!!) 3/4-inch bolts holding it together and they all have to be removed and then the 50-pound top half lifted off. Then there's a huge $30 o-ring between the two halves that may or may not seal again after it's been squished for a long time. Last time, I also spent another hour cleaning the rusty threads on all of those bolts and putting anti-seize lube on them so it would go a bit easier next time (we'll see in a couple days), but I suppose that could be replaced with a squirt of WD-40 if done every year.

 

[mknauss]

I would suggest you review the following Deep Cleaning a Sand Filter

The section recommending the time frame for a deep clean starts at

The Ultimate Deep Clean

 

[BrianR170]

Brian, if you can get the top off the sand filter (that multiport valve usually) and lift off any surface schmutz then put a hose in the sand gently down in the sand (so as not to go so far in and disrupt a lateral) you can turn the water on and let the gunk float up and out of the top. Keep that up until the water runs clean.

The filter looks like this (photo of the same model I found using Google search)


I'm not sure if the "gunk" will come out so easily. If it's like before, I'd guess at least 50 lbs of mud, but probably much more. If that much were to come out with the deep cleaning, it seems like it would make a pretty big mess.

I think what I'll do is scoop out some of the mud into a 5-gallon bucket and take it out by the curb and see what happens when I deep clean it. Who knows, maybe it's not like I remember, or maybe there just won't be so much like last time. The neighborhood was brand new 24 years ago and surrounded by a lot of desert and construction. Dust storms blew a lot more dirt and dust into the pool back then.

You need to backwash when your gauge rises 20% over *clean filter pressure*. That may or may not be the 15-17psi you currently use as your mark. Once you clean your filter (and replace any missing sand needed) make note of your clean pressure reading for reference.

It's just over 10psi when the sand is new and clean. This is what it was 24 years ago when they first built the pool and also right after I changed the sand 12 years ago. The pool builder said it would settle to 12psi after the first year and he was right, 12psi is the minimum pressure after about a year and even a 30 minute backwash won't make the pressure drop to 11psi. The builder also said to backwash at 18psi, but I found that the pool cleaner works better if I never let the pressure go above 15psi. Backwashing at 12psi (20% above the 10psi clean pressure) would make for twice-a-week backwashes in July and August, but I will try it if it keeps the mud from building up in there without me having to disassemble the filter.

You sand is millions of years older than just the 12 years you've had it. Let it work for a few hundred more,'k?

Maddie

Totally agree and I'm all for re-using it as long as it's practical.

 

[YippeeSkippy]

um...<shuffles feet>...after seeing all those bolts...well.. I think I'd tell Skippy buy us a new sand filter with a lot fewer bolts! HOLY COW!

Maddie

 

[sktn77a]

You can get a new Hayward sand filter with MPV in that size for about $400 on a good day.

 

[BrianR170]

I deep-cleaned the sand in my Sta-Rite HRPB30 yesterday. Opening up the filter looks like this:



I knew the normal level of the sand is right at the level where the two halves of the filter come together, but with all the extra debris, it's actualy about 1 inch higher. So, I also knew that I would have to do at least some of the deep cleaning somewhere else. My plan was to scoop the sand into 5-gallon buckets and deep clean it on the end of my driveway to reduce the mess in my yard. What I found from the experience with "bucket washing" the sand is that it works extremely well because you can get your hand down in the bottom of the bucket to break up the clumps and move the hose around. The water comes out extremely dark at first and clears up after a minute or two of washing. I also found that the level of the sand needs to be at least 6 inches from the top of the bucket to keep from washing away the sand along with the other debris.


So, I kept washing the sand in buckets and saving it in a pile on my patio until the level of sand in the filter was about 6 inches below the top of the filter, then I disconnected the filter and deep-cleaned the remaining sand in the filter. Of course, when the sand level was down 6 inches, I had already removed about 2/3 of the sand in the filter, and the filter and remaining wet sand still weighed well over 200lbs.

The cleaned sand back in the filter looks like this.




The whole process took nearly 4 hours with over an hour dedicated to just the initial disassembly and final reassembly of the filter. My personal opinion is that for do-it-yourselfers who own the Sta-rite HRPB30 (or HRPB24 or HRPB20), deep cleaning your sand is feasible, it's environmentally friendly, it saves a little money, and it's kind of satisfying. However, for the time-conscious, it might not be very practical. I spent 2 hours worth of hard work washing the sand and disconnecting/reconnecting the filter lines that I could have saved by just replacing the sand instead of cleaning it. Of course replacing your sand assumes you have somewhere to dump 400+ pounds of dirty sand. Also, maybe with different tools you could save yourself some time (e.g., a couple of large/deep wheelbarrows that you could use to remove and wash all of the sand at once without having to dump any of the sand on the ground or disconnect the filter).

 

[needsajet]

Wow, great job on the cleaning! Good outcome at least, and thanks for the heads-up for others with that filter type. How much did your clean pressure change?

 

[BrianR170]

How much did your clean pressure change?

Not much. It's around 11.5psi.