Cleaning out Spot free tank

[OurTown]

We have an underground poly tank for our spot free water that I think is 1,500 gallons. I returned the bypass on the pumps back to the tank a few months ago. Ever since then the new return hoses are kicking up sediment from the bottom of the tank so we have to clean our strainer screen much more often. The TDS at the bay checked weekly is still 11-13 and hasn't changed since we bought the wash in August. Is there an efficient way to get the sediment off the bottom without emptying the tank? We were thinking of a pool vac setup. I'm sure it hasn't been cleaned since the wash was built 15 years ago.

 

[I.B. Washincars]

I've sucked the gunk out with a piece of PVC pipe and hose plumbed to a Flojet.

 

[washnvac]

I usually will turn my production off a day before rain, to let the tank run down. Then I just finish emptying it and use a shop vac with a long hose. If it is real bad, I will get in there to get every nook and cranny. I do it every 5-8 years.