Wednesday, August 26, 2015

Spin Down Filters: How to Determine What Mesh Size to Use?

Question…how do I determine what size mesh filter to buy?
When I fill and drain the tub without bathing there is a layer of chalky or talc like sediment covering the bottom and sides (when allowed to dry)
William S.

This is a good question and it comes up often.  In general, we recommend using the coarsest mesh size deemed acceptable to filter the materials you want to remove. This will help to extend the life of your system and reduce how often the filter requires cleaning.

Mesh size is all about the number of holes per inch. You have to choose the mesh size according to the type of sediment you're trying to get rid of. In choosing the right mesh filter size, you get to extend the life of your system and you won't need to clean your filter too often. Lower mesh filter sizes are for coarser mesh while higher mesh filter sizes are for finer mesh. 
See how it works:
mesh diagram

Here’s the general mesh filter sizing guide:
Materials in Water
Systems To Protect
Recommended Mesh Size
Micron Rating
Shale, Shell
General use
711 micron
General use
#24, #30, #40
533 -381 micron
Pipe Scale, Coarse Sand
Sprinkler systems, sensitive valves, factory aerators
250 micron
Fine Sand, Grit from New Wells
Drip irrigation systems, sensitive valves, poultry growers, watering devices, fogger nozzles
#100, #140
150 – 105 micron
Very Fine Sand and Grit
Pre-treatment for RO, UF systems, etc
#250 - #1000
61 – 15 micron

It could potentially clog up the screen and require frequent cleaning.  In some cases, it really can require finer filtration like a very fine cartridge filter, or flocculation, or ultrafiltration.  White chalky material might also just be calcium carbonate or sodium bicarbonate buildup, in which case you would need a more specific type of treatment like a water softener or reverse osmosis. 

You reported you have a layer of chalky or talc-like sediment.  This doesn’t exactly match any of those materials descriptions above, and in many cases, that kind of clay-like material can actually be pretty problematic for mesh screens. 
Luckily, it’s inexpensive and simple to try out a mesh screen first and see how it works first.  Out of any of the screen sizes, I would suggest a 100-mesh size and seeing how that works for you.
A water analysis is recommended.  Many of our customers start with a good water analysis of their well water, which can help identify the problem. Click on this link to view our water testing kits. They're accurate and super easy to use!