Thank you jblizzle very much for the time to write the sticky on cleaning a DE filter and for all the good pictures. http://www.troublefreepool.com/threa...aning-Tutorial I would never have attempted to clean up my filter and give it a once over without the confidence and information provided there.
I would like to share my experience with cleaning my filter grids from a Hayward 3600DE Microclear. I am the second owner and the filter is 14 years old although the grids are likely replacements. This filter operated okay the first two of seasons I used it, with occasional back washing and recharging. Last season it needed a couple of additional back washes.
Getting ready for start of this season I thought I would give the grids a good cleaning and wash. Based on how long the grids were holding water after a good spraying and further reading here, I decided to do an acid wash. I proceeded to break the filter down to fit the individual grids into a large trashcan much easier than the whole assembly. I noted a few of the internal plastic frames were cracked and a few small holes in the fabric, but didn’t really closely inspect them at this point.
I followed the directions in this sticky and some of the forum posts like http://www.troublefreepool.com/threa...for-DE-filters to give them a TSP wash (5 cusp in 25 gallons) and soak for 4 hours. That went well and the TSP removed a bunch of gunk. I hosed them off thoroughly and decided to use a mixture of dry acid (sodium bisulfate) versus muriatic acid (its what I had on hand). I spent lots of time researching the quantity of dry acid to use and could not quite figure out the conversion, and decided to stay on the side of caution. I went with dissolving 6 pounds in three gallons of warm water then added to the can and filled to approximately 25 gallons. This seemed to go well as there was limited visible reaction upon inserting the grids. I soaked them for 4 hours in that mixture then rinsed them well. There was a noticeable difference in the time required for the grids to drain water so I considered this a success.
It took approximately 10 lbs. of baking soda to neutralize the 6 lbs. of acid in 25 gallons of water. I then soaked the grids in 2lbs of baking soda mixed with another 25 gallons of water to ensure they were acid free.
I let them air dry overnight and then inspected them. This inspection was easier after they were dry and revealed the bad news. Five of the grids suffered at least one or a combination of the following: notable series of holes along the vertical inner edge; significant cracks in the internal plastic frames near outer corners; holes that were beginning to form where either the top or bottom manifold alignment slots were wearing them; and pencil eraser size shredded areas where the fabric was separating at the bottom of the central tubes. Other than the cracked corners, none of this damage was readily apparent while the whole unit was assembled.
At this point I figured I was fighting a loosing battle if I attempted repairs and decided to get a replacement set of grids and purchased them locally for $175. About $25 more than some of the online retailers I found.
The last thing I wanted to do was limp to the middle of summer and find my filter blowing DE into the pool one warm Saturday afternoon and have to deal with it on short notice. Assembling the whole thing with new grids was pain free and my start up pressure was 5 pounds lower than last year.
Things I learned and take away notes for my future reference:
1. Older grids should be periodically and thoroughly inspected by removing them from the manifolds.
2. Use muriatic acid for the wash (if its necessary), a trip to the store to buy the right product would have saved my dry acid volume research time. (That research had a benefit though, as I learned a few things about the dry acid and plan to switch to muriatic to reduce PH in the future.)
3. Thoroughly rinse and let the disassembled grids dry prior to a first inspection - BEFORE beginning the soap and acid cleaning process. This would have saved me time and money trying to clean up grids that really needed to be replaced.