Adding DE To Sand Filter

I'm trying to get better filtration from my sand filter by adding DE. Pool school says 1-2 cups should typically give me a 1psi pressure rise. It took 5 cups to get that 1psi rise. 300lbs of sand in the filter as per spec. Why is so much DE required with my system? I just rechecked pressure 6hrs after I introduced the DE into the system and it is up an additional 0.5psi which I attribute to contaminants being cleaned out of the water. Water is clear and properly balanced.
 

duraleigh

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I would first ask what is wrong with the water clarity without adding DE? Do you have a pic of your water?
 
Nothing is wrong with water clarity it is crystal clear as I just did a recent water change to drop CYA. Just looking for the best filtration I can achieve. When the old water was in the pool it was clear as well however small particles could be observed when swimming. I'm just trying to keep the new water as clear as possible. I'm
curious as to why my system takes well over double the max numbers the article says. The sand has one season on it but the equipment is of unknown age. Wondering if any insight can be drawn from this anomaly.
 

Flying Tivo

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Monterrey, NL, Mexico
Sand is a million years old, it does not go bad. One thing you need to know is that a slightly dirty filter helps to filter smaller particles. So dont backwash often, only when pressure rises 25% above clean preasure. Adding DE works in the same way as making your sand a little more dirtier.
 
Sand is a million years old, it does not go bad.
That is incorrect. When sand is used in a pool filter it will eventually have the sharp edges on the individual grains worn down and rounded off. Because of this, it's ability to trap particles will be greatly reduced. Also makes it more prone to channeling in the filter. That's why it must be periodically replaced.
 
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duraleigh

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When sand is used in a pool filter it will eventually have the sharp edges on the individual grains worn down and rounded off.
When do you think that "eventually" occurs and it's time to change sand because it is worn out? Do you have a time frame?
 
That would be based off flow from the pump as it's creating the abrasion amongst the particles forcing water through them to the laterals. For me it was time to change sand last season as the pool got cloudy and could not be remedied until the sand was changed. Once I did that was less than 48hrs and it was sparkling again.
 

duraleigh

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TFP suggests that sand NEVER be changed. As flying tivo said, it laid on the beach for millions of years and a couple of years inside your filter is irrelevant.......UNLESS you hopelessly clog up your filter with some additives that should never have been in there in the first place.

Deep Clean your sand once yearly (or thereabouts) and the sand will outlast you and your children's children.

The sand in my pool is 14 years old now, the water is crystal and the sand will never be changed.
 
Going to have to agree to disagree on that. My original post was in regards to DE volume in a sand filter not on sand life expectancy. TFP recommended something on there as well that is way off scale, not a stretch to think that's the only point they missed the mark on.
 

duraleigh

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TFP believes folks should care for their pool in any manner they like.

This is a teaching forum not meant for arguing.

We teach what 235,000 members and over 1.8 million posts have found to be factual and effective. It is entirely your choice to take that collective knowledge and disregard it but likewise you do not have the freedom on this teaching forum to promote things which we know to be incorrect.
 
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duraleigh

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Sorry. Your original question should have been addressed. Unfortunately, I have no idea. It could be the gauge is inaccurate or sticky but you would know that better than us.
 
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kimkats

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In answer to the amount of DE needed:

I have found that each pool and equipment set up is VERY different. One filter only liked 1/4 cup of DE to react to it. Mine likes 2 cups of DE. We have the same size sand filter! I have an above ground and they have an in ground. I have a 2 speed pump. They have a VS pump.

The above needs are why I try to make sure to tell anyone wanting to try DE in their sand filter to make sure they can be there to baby sit it the first time they add it. That way they can do a backwash if the pressure goes up too far.
 
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Flying Tivo

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When sand is used in a pool filter it will eventually have the sharp edges on the individual grains worn down and rounded off.
Maybe the type of sand in the northwest is older than ours down here in Mx and needs to be changed more frequently. But you are totally right that we did not answer your question. My best guess is that its dependent on surface area of the sand, some have more or less sand when filled.