Filter Type Choice - Backwashing to woods - Also have well

MassNerd

LifeTime Supporter
Apr 27, 2013
174
Central Massachusetts
Hi,
I've got the PB coming over tomorrow to work out the final details of our IG Vinyl pool install. I've learned a lot reading Pool School and the forums. This is a great site!

However, I'm still stumped on filter choices. I'm leaning towards a DE filter, but my #1 concern is about the safety of the backwash. Let me tell you about my setup and proposed equipment:

~18K Gallon IG Vinyl pool
SWCG - Hayward Aqua Rite
Heat Pump - AquaComfort 125K BTU
I will be backwashing onto lawn + woods (About 0.75 acre is behind the pool half wooded)
I have well water, also in the back yard


So what filter type would you get?

At first I was concerned about the SWCG and backwashing to the lawn/woods but I've now read the salt ppm is too low to harm plants, plus I have the ability to backwash to many different areas (lots of land, distribute the salt better).

However, there seems to be some concerns over the safety of DE. Its not allowed in sewers. With my setup should I not backwash DE onto my land?
 

JohnT

Admin
Mod Squad
TFP Expert
Apr 4, 2007
9,900
SW Indiana
Re: Filter Type Choice - Backwashing to woods - Also have we

DE is not dangerous unless it is an airborne dust.

If you live in an area where there is a lot of dirt and debris in the air, a sand filter may be the best choice since sand can handle high dirt loads and cleaning is trivial.

Before you make a decision, I would highly recommend that you have your well water tested so that you know what your make-up water source is going to be like. If your well water isn't suitable for filling the pool, you probably want to go with a cartridge filter to save the water that would otherwise be lost during backwashing. Calcium hardness, iron and alkalinity would be your main concerns.
 

Isaac-1

TFP Expert
LifeTime Supporter
May 10, 2010
6,711
SW Louisiana
Re: Filter Type Choice - Backwashing to woods - Also have we

Dry DE is an inhalation hazard, otherwise it is used in gardening, etc. (well the gardening type is also a bit less of an inhalation hazard as it is more rounded), as to environmental issues, from what I have read regarding discharge to sewers it seems to mainly be a concern with it causing damage to treatment plants (I am not sure exactly how though), and when dealing with discharge into ecologically sensitive areas.
 

Richard320

TFP Expert
LifeTime Supporter
Jan 6, 2010
23,932
San Dimas, CA (LA County)
Re: Filter Type Choice - Backwashing to woods - Also have we

Ditto on the windblown dust and well water concerns.

That being said, if DE looks viable, do it, but use cellulose media. Some ultrarefined sawdust won't hurt anything. My lawn seems to thrive on the backwash. Although I don't use salt in my pool.
 

MassNerd

LifeTime Supporter
Apr 27, 2013
174
Central Massachusetts
Re: Filter Type Choice - Backwashing to woods - Also have we

Thank you all for the helpful advice.

I do have water test results, but not with me so I'll post them later tonight.

Richard, can you elaborate on how you judge whether a DE filter is viable in my situation? Anything other than my concerns or those raised in this thread? So far I'm interpreting the feedback in this thread to be "OK to get a DE as long as I have a good water source to refill water lost to back washing. ". I suppose the same would apply to a sand filter as well since it requires more backwashing.
 

Richard320

TFP Expert
LifeTime Supporter
Jan 6, 2010
23,932
San Dimas, CA (LA County)
Re: Filter Type Choice - Backwashing to woods - Also have we

MassNerd said:
Thank you all for the helpful advice.

I do have water test results, but not with me so I'll post them later tonight.

Richard, can you elaborate on how you judge whether a DE filter is viable in my situation? Anything other than my concerns or those raised in this thread? So far I'm interpreting the feedback in this thread to be "OK to get a DE as long as I have a good water source to refill water lost to back washing. ". I suppose the same would apply to a sand filter as well since it requires more backwashing.
Mostly it's the dust and debris. A DE filter will load up really fast if there's a lot of dust, like farmers fields or a dirt bike track nearby. You already know if that's the case - just look at the car, the window sills, and the patio furniture. Sure, the water is super clean, but you'll be backwashing constantly.

Second, if you have poor quality well water, you'll be adding more metals or whatever every time you backwash a sand or DE filter. A cartridge filter needs less water to clean it, and it's not coming from your nice balanced pool water.
 

Isaac-1

TFP Expert
LifeTime Supporter
May 10, 2010
6,711
SW Louisiana
Re: Filter Type Choice - Backwashing to woods - Also have we

To follow up Richards second point, this is true if your well water is so bad that you need to treat for metals, or haul water in, if it is below that point then backwashing with DE or Sand filters can help lower the levels in your pool, as they would otherwise build up due to water evaporation. As you would be refilling with somewhat lower concentrations from your well water.
 

Bow_Extreme

Active member
Jun 1, 2012
40
Grand Rapids, MI
Re: Filter Type Choice - Backwashing to woods - Also have we

Richard320 said:
MassNerd said:
Thank you all for the helpful advice.

I do have water test results, but not with me so I'll post them later tonight.

Richard, can you elaborate on how you judge whether a DE filter is viable in my situation? Anything other than my concerns or those raised in this thread? So far I'm interpreting the feedback in this thread to be "OK to get a DE as long as I have a good water source to refill water lost to back washing. ". I suppose the same would apply to a sand filter as well since it requires more backwashing.
Mostly it's the dust and debris. A DE filter will load up really fast if there's a lot of dust, like farmers fields or a dirt bike track nearby. You already know if that's the case - just look at the car, the window sills, and the patio furniture. Sure, the water is super clean, but you'll be backwashing constantly.

Second, if you have poor quality well water, you'll be adding more metals or whatever every time you backwash a sand or DE filter. A cartridge filter needs less water to clean it, and it's not coming from your nice balanced pool water.

Not to impede on the original posters filter question but I have both of the conditions you mention. I currently have a sand filter but it and the pool are not setup yet. Should I purchase a cartridge filter instead? If so, what size and type do you recommend? 17,000+ gallone above ground SWG pool.

Thanks to the original poster for asking the question.
 

Richard320

TFP Expert
LifeTime Supporter
Jan 6, 2010
23,932
San Dimas, CA (LA County)
Re: Filter Type Choice - Backwashing to woods - Also have we

I have no experience with cartridge filters. Sorry, can't help you size one.

How bad is your water? I mean...rust stains in the toilets and so on? Because a sand filter sure is easy to clean. Turn a lever and let 'er rip. No recharge, no breaking down to clean grids. And if you want a little better filtering, you can add a little DE to a sand filter.
 

kevreh

In The Industry
Jun 2, 2007
457
Annandale, VA
Re: Filter Type Choice - Backwashing to woods - Also have we

I bought a new DE filter a year ago. But based on what I hear from the pool pro's I talk to, buying a sand filter but using something like the glass spheres or zeolite makes the 'sand' filter close to DE, with filtration down to 3 microns. I like that you can backwash as much as you want without buying more DE.
 

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jblizzle

Mod Squad
TFP Expert
LifeTime Supporter
May 19, 2010
43,238
Tucson, AZ
Re: Filter Type Choice - Backwashing to woods - Also have we

Bow_Extreme said:
Not to impede on the original posters filter question but I have both of the conditions you mention. I currently have a sand filter but it and the pool are not setup yet. Should I purchase a cartridge filter instead? If so, what size and type do you recommend? 17,000+ gallon above ground SWG pool.

Thanks to the original poster for asking the question.

For 17,000 gallons minimum recommended sizes:
252 sqft cart
3.1 sqft sand (24")
47 sqft DE

For further discussion, please start your own thread.
 

Bow_Extreme

Active member
Jun 1, 2012
40
Grand Rapids, MI
Re: Filter Type Choice - Backwashing to woods - Also have we

Richard320 said:
I have no experience with cartridge filters. Sorry, can't help you size one.

How bad is your water? I mean...rust stains in the toilets and so on? Because a sand filter sure is easy to clean. Turn a lever and let 'er rip. No recharge, no breaking down to clean grids. And if you want a little better filtering, you can add a little DE to a sand filter.

I would have stains if it weren't for my water softener system. Yes we have high iron levels in the area.
 

MassNerd

LifeTime Supporter
Apr 27, 2013
174
Central Massachusetts
Re: Filter Type Choice - Backwashing to woods - Also have we

I couldn't find the full water report from 2 years ago, but when I get my water softner/filter serviced this is what I've seen over the years for the untreated water:
pH usually 7.5 but as low as 6.9
Alkalinity between 60-100
Hardness = 4-8
Iron = 0.7-1.0
We are known for high iron in the water in this area. If I didn't have the softener then we'd have pink stains on the sinks and toilets
 

JohnT

Admin
Mod Squad
TFP Expert
Apr 4, 2007
9,900
SW Indiana
Re: Filter Type Choice - Backwashing to woods - Also have we

If your well water has iron, I would investigate having water hauled for the pool. Iron tends to precipitate when you add chlorine to the water, staining the pool surface.
 

MassNerd

LifeTime Supporter
Apr 27, 2013
174
Central Massachusetts
Re: Filter Type Choice - Backwashing to woods - Also have we

I've decided to go with a Hayward S244T sand filter filled with zeobrite. I will have the initial fill trucked in of course. Any pool top up I'll be doing from the garden hose I will filter through my 4.5" x 20" sediment filter. It seems you can get a $80-100 filter that filters out up to 3ppm iron for 40,000 gallons of water. So that is cheaper than buying cartridges ever few years and solves my water source concerns.

Thanks for the input everyone!
 

kevreh

In The Industry
Jun 2, 2007
457
Annandale, VA
Re: Filter Type Choice - Backwashing to woods - Also have we

Sounds good. Thats the filter solution I would probably do that too if I hadn't bought a new DE filter a year ago. DE's not a big deal, but I've had to backwash 3-4x this spring considering the algea I had (wasn't too bad, I just didn't shock before closing and the rain over the winter added a lot of water).
 
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