Should I Switch Form 1 1/2" To 2" Pvc Pipes?

[Gavin]

Gavin, Has the pressure always been high? Or is this something that has happened recently?

its built up over time. I think I need to give it a good clean. I just hosed it down with some acid and water but I think I need to use some of that TSP and water...soak it well in that and maybe also some acid.

[Pool Clown]

Ok, then i wouldn't stress out over replacing all the plumbing or the pump. Just clean the filter media. If it doesn't clean up, then you may have to replace the (filter) tubes. Start there, and change that pressure gauge if it's not accurate.

[Gavin]

Ok, then i wouldn't stress out over replacing all the plumbing or the pump. Just clean the filter media. If it doesn't clean up, then you may have to replace the (filter) tubes. Start there, and change that pressure gauge if it's not accurate.

I took everything apart and removed the flex tubes and soaked then in 1 part muriatic acid to 5 parts water for 20 minutes. then reinstalled and now the pressure gauge is reading 12psi!!

and the return jets are working 3 times as well! lots of water moving! Thanks a million guys!!

btw SF is 1.1

[quantumchromodynamics]

12 psi sounds about right. For your system, I would estimate about 9-11 psi with no directional eyeballs, 11-13 psi with 1-inch eyeballs and about 12 to 14 psi with 3/4-inch eyeballs.

Since the EC-65 does not backwash well, it helps to take it apart periodically to give it a good cleaning.

[Gavin]

12 psi sounds about right. For your system, I would estimate about 9-11 psi with no directional eyeballs, 11-13 psi with 1-inch eyeballs and about 12 to 14 psi with 3/4-inch eyeballs.

Since the EC-65 does not backwash well, it helps to take it apart periodically to give it a good cleaning.

you guys are amazing! Thanks!

[Mark]

To me 12 PSI would indicate a bit more head loss on the suction side than a normal setup. The only way I can get to 12 PSI for an up rated 1 HP pump is if there is only a single suction run from pool to pad adn slighly longer runs on the suction side which to me is not a normal setup for 1 1/2" plumbing. If there were 2 suction lines, I would have expected something closer to 16 PSI and much better flow rates. 12 PSI indicates low flow rates for that pump.

Gavin, can you describe your plumbing setup in a bit more detail. How many suction/return lines and how long? This is more of a curiousity than anything else.

[quantumchromodynamics]

I have 3 suction lines: main drain, skimmer and vacuum. They are 1 1/2". I think the return is 1 1/2"...will need to double check that. my pump and filter is about 2ft above the pool if that makes any difference in pressure? - Gavin

He doesn't say if he keeps the main drain open or not. I would assume that the vacuum is kept closed. The fact that the pump and filter are about 2 feet above the pool water level will make the pressure read about 2 psi lower at the gauge (Assumes that the gauge is about 4.62 feet above the water).

Therefore, that makes the actual pressure about 14 psi. For a 1.0 H.P Superpump (Assumed SP2607X10 Superpump)* with a service factor of 1.1, I get about 47 gpm at 47 feet of total head.

If we assume that the head loss due to the filter is about 12 feet (The EC-65 has only about 27 square feet of surface area. It is rated at 54 gpm.), that leaves about 14.7 feet for the suction and about 20.3 feet of head for the pressure plumbing.

That gives an equivalent of about 114 feet of straight 1.610 I.D pipe for suction and 157 feet of straight 1.610 I.D pipe for pressure. The returns do have directional eyeballs so that will account for some of the head loss.

*The Superpump is typically sold with the EC-65 and base as a package as shown in this picture.

[Mark]

I agree and I get similar numbers but only if I assume that there is only one suction line open which is why I asked the question. If there are two suction lines running at the same time with 1/2 the flow each, then I get a filter pressure closer to 15 PSI and the flow rate increases to 50 GPM @ 43' of head. So it may just be that the main drain is off.

One more thing. With the single suction pipe, I get a vacuum at the pump close to 14" so it wouldn't surprise me if there was air in the pump basket.

[Gavin]

I agree and I get similar numbers but only if I assume that there is only one suction line open which is why I asked the question. If there are two suction lines running at the same time with 1/2 the flow each, then I get a filter pressure closer to 15 PSI and the flow rate increases to 50 GPM @ 43' of head. So it may just be that the main drain is off.

Hi Mark, There are 3 suction lines...main drain, skimmer and vacuum. Vacuum I keep closed unless I'm vacuuming...then I shut off main drain and skimmer.

its an old hayward pump. bearing are making a little bit of a noise and one day will need changing or changing the pump.

[Gavin]

now I have another problem. my EC65 DE filter doesn't seem to be backwashing properly.

last time I backwashed for a good amount of time. I even bumped in between backwashes like you guys recommended. But when I opened up the filter there was sludge on some of the fingers and also at the bottom of the filter.

I know these DE filters don't really backwash but I thought at least they'd clean out the sludge from the fingers and the bottom of the filter. I don't know whats going on. after I cleaned the filter yesterday it was working so well but after I vacuumed today I came back 4hrs later and the filter was clogged up and pressure was 25psi again. when I bumped it drops back down to 12psi. but I can't keep bumping all day long. I guess I will have to open the filter up and manually clean the sludge out. backwashing doesn't seem to be working.

maybe I'm putting too much DE powder in. I bought one of those 1lb DE scoops. I put in 2 scoops to recharge. thats 2lbs of DE for a EC65. maybe I should try only 1lb?

oh I think I've been backwashing wrong. I watched this video and they say to bump the handle when backwashing with the pump on the same time. ah ha!

I will try this tomorrow. but is 2lbs too much DE to recharge?

Thanks.

[Mark]

Gavin,

So are you saying that the 12 PSI is with both the main drain and skimmer lines open? And to be absolutely clear, both the skimmer and main drain have separate pipes all the way back to the pad?

[Gavin]

Gavin,

So are you saying that the 12 PSI is with both the main drain and skimmer lines open? And to be absolutely clear, both the skimmer and main drain have separate pipes all the way back to the pad?

both main drain and skimmer are kept open.

I only see the pipes coming up through the pad and then all three join and go to the pump. I'll take a pic in the morning. but I don't know where they go or how they are under the ground. all three..in fact all the pipes are 1 1/2".

[quantumchromodynamics]

Ok, if we assume 55 gpm at a total head loss of 38 feet, then we can balance with:

Filter head loss of 12 feet.

Return head loss of 20 feet = 116 feet equivalent 1.610 I.D straight pipe at 55 gpm.

Suction head loss of 6 feet (5.296" Hg (inches of mercury)) = 126 feet equivalent 1.610 I.D straight pipe at 27.5 gpm.

Dynamic head only, as static head will cancel. Actual total suction head = 8 feet, filter = 12 feet and return =18 feet.

http://www.haywardnet.com/pdfs/SuperPump_LITSUPER07.pdf

[Mark]

38' of head loss for 1 1/2" and a 1 HP Superpump would be well on the low side of what is typical. Best efficiency point is 52 GPM @ 42 ft of head so 38' of head would require the pool builder to do a very low head loss design which is not very typical of 1 1/2" plumbing pools nor typical of most pool builders. Most 1 1/2" plumbing that I have seen over the years is far to the left of the BEP point on the head curve.

Given that the pump is an older pump with bearing noise, it is far more likely that the pump impeller has been damaged in some way and not producing the flow rates it once was.

[quantumchromodynamics]

I have seen many such systems with the same pump, filter, and 1.5 inch plumbing. I would estimate that in about 90 + % of cases, the pressure is 9-11 psi with no directional eyeballs, 11-13 psi with 1-inch eyeballs and about 12 to 14 psi with 3/4-inch eyeballs (2 returns).

Also, the poster does specify that they have 4 returns.

Note: The SP2607X10 is actually a 3/4 H.P full rated pump with a Service Factor of 1.47 or a max-rated 1.1 H.P pump.

[Gavin]

I back washed again but was not able to bump while pump was on as handle was too stiff and I didn't want to damage the filter. so bumped in between. I then opened the filter up and it was clean so it is back washing fine now. however I decided to just recharge with 1lbs of DE to be on the safe side and keep pressure down. I think 1lb should be sufficient for this filter to clean the water and won't clog up the filter and back washing will work better.

The filter pressure is now 10psi.

[Mark]

I have seen many such systems with the same pump, filter, and 1.5 inch plumbing. I would estimate that in about 90 + % of cases, the pressure is 9-11 psi with no directional eyeballs, 11-13 psi with 1-inch eyeballs and about 12 to 14 psi with 3/4-inch eyeballs (2 returns).

Also, the poster does specify that they have 4 returns.

Note: The SP2607X10 is actually a 3/4 H.P full rated pump with a Service Factor of 1.47 or a max-rated 1.1 H.P pump.

The SP2607x10 is the uprated version, the full rated version would not have the x10 at the end. Anyway that is the pump for which I quoted BEP.

Also, I don't take issue with the PSI readings. There are nearly infinite combinations of suction and return equivalent lengths to get to 12 PSI but they will change the operating point.

My primary objection was the operation point. Most 1 1/2" plumbing pools that I have delt with in the past are older pools and thus were not designed all that well for head loss so most of them tend to operate on the left side of BEP by a good margin. What you were proposing was an operational point that was to the right of BEP which I think is very unusual for older style 1 1/2" pool plumbing. Also, older pumps generally fall off their published head curves after so many years of running so it is not so unusual for them to deliver less flow rate than normal. Impellers can get chewed up over time and are not as efficient at delivering flow rate. In my opinion, it just seems more likely the pump is producing less flow rate than the plumbing being better than average.

[quantumchromodynamics]

My primary objection was the operation point. Most 1 1/2" plumbing pools that I have delt with in the past are older pools and thus were not designed all that well for head loss so most of them tend to operate on the left side of BEP by a good margin. What you were proposing was an operational point that was to the right of BEP which I think is very unusual for older style 1 1/2" pool plumbing.

I guess I don't see how it would work with the operation point "on the left side of BEP by a good margin".

If we assume that the pressure at the gauge is 10 psi (reported in the latest post), that gives us 12 psi dynamic head when we account for the static height of the gauge above the water. 12 psi = 27.72 feet of head.

If we go a little bit to the left of the BEP and choose 50 feet of total head, then we get 40 gpm.

50 feet of head - 27.72 feet for the pressure side leaves 22.28 feet of head (19.67 inches of mercury) for the dynamic head for the suction (21.43 inches of mercury or 24.28 feet of suction head if measured by a gauge at the pump). That's way too high for suction.

There are two 1.610 I.D suction lines. If they each carry 20 gpm, then the equivalent effective length of straight pipe is 841 feet.

There is one 1.610 I.D return line. If we assume 22 feet of head for the return, at 40 gpm it would take the equivalent of 230 feet of straight pipe. The return actually Tees off underground to 4 returns, so that makes 230 feet even more unlikely.

I think that my earlier example of the return plumbing being equal to 116 feet of straight pipe and the suction being the equivalent of 126 feet of straight pipe makes more sense. I just don't see how the plumbing is going to work out to more than that unless the plumbing is extremely long and chock full of 90s.

The pump and filter are usually within 40 to 60 feet of the pool and there shouldn't be more than about (5) 90s. That comes out to around 80 to 130 feet.

Also, the suction and return should be fairly close in total equivalent length. 116 and 126 makes sense. 841 and 230 don't add up.

______________________________________________________

Also, older pumps generally fall off their published head curves after so many years of running so it is not so unusual for them to deliver less flow rate than normal.

If we assume that the pump has fallen off of its curve and is delivering less flow than it should at a particular head, then that actually makes it worse.

Example: 42 feet of head and 42 gpm (instead of 52 gpm). We still get 27.72 feet of head for the return because that is what the gauge reads. There is one 1.610 I.D return line. If we assume 22 feet of head for the return, at 42 gpm it would take the equivalent of 210 feet of straight pipe. At 52 gpm, it would take the equivalent of 142 feet of straight pipe.

42 feet of total head - 27.72 = 14.28 feet of dynamic suction head. At 21 gpm, the equivalent effective length of straight pipe is 493 feet for suction. At 52/2 = 26 gpm, we get the equivalent effective length of straight pipe is 332 feet for suction.

This example is right near the BEP. If it were to the left of the BEP, then the figures would make even less sense. I think that this particular system curve meets the pump curve to the right of the BEP.

Note: The SP2607 and the SP2607X10 are the same exact pump, just labeled differently.

The SP2607 is labeled as a 3/4 H.P full rated pump with a Service Factor of 1.47.

The SP2607X10 is labeled as a max-rated 1.1 H.P pump.

[Mark]

I think you missed my point. If the equivalent length of pipe is higher than what you assumed for a typical pool with 1 1/2" plumbing, which usually is from my experience, then with a fully functional pump, the PSI would start out higher. If there was a problem with the impeller, the entire head curve would shift down and to the left, much like it does with an impeller trim or an RPM change. The flow rate would drop and so would the PSI which could also explain why the PSI is lower. The BEP point also moves down to the left.

For example, if you assume the following:

Suction: 127' of eq pipe (2 runs)

Pad w/filter: 150' of eq pipe

Return: 127' of eq pipe

I get a operating point of 51 GPM @ 43' of head (14.4 PSI), which is slightly to the left of BEP. If you now assume the head curve shifts down and to the left by 15% due to a plugged or broken vane (1 of 6), then the operating point becomes 43 GPM @ 32' of head (10 PSI).

My main point is that there could be other operating conditions that get you to 10 PSI, including a plugged impeller, a partially plugged suction line or even a bad gauge. I just think it is a good idea to make sure there isn't a problem somewhere else. A plugged impeller or suction line is not uncommon, especially right after vacuuming, and should not be dismissed so easily. If it was my pool, I would check some of these things.

Gavin,

I would also be interested in knowing how far the pad is from the pool and if you have a picture of the pad.

[Pool Clown]

Sorry Gavin, Looks like the Hydraulics lab has kicked you to the curb even after your problem was resolved. I'll try to answer your post.

I decided to just recharge with 1lbs of DE to be on the safe side and keep pressure down. I think 1lb should be sufficient for this filter to clean the water and won't clog up the filter and back washing will work better.

The filter pressure is now 10psi.

Careful, don't think that less D.E. is better. It could be worse. Those "tubes" in the filter are not really the filter, the D.E. that coats the tubes is really the filter. If you don't get the proper amount of DE on them, then the debris can get impregnated into the mesh of the tube (because it is exposed or partially exposed), and you could wind up back here with the same problem.

Find out for certain how much DE you need for that filter and apply that much. I think i read that you have a 1 lb. scooper? Make sure it is for DE, cuz DE is a lot less dense than just about everything else.

Example: a 2 lb coffee can is about equal to 1lb of DE.

Good Luck

[quantumchromodynamics]

I think that the primary issue has been a dirty filter. Once the filter was cleaned, the pressure went down to the correct level.

Gavin, the EC-65 takes 6 pounds of DE. That is how much you should add after you disassemble the filter and clean it. After backwashing the filter, you should add the amount of DE that was lost due to backwashing.

As PC notes, the filter needs the correct amount of DE to function properly.

If you can catch the DE somehow, that can help you determine the amount lost and how much you need to add.

Most pool stores sell a one-pound DE scoop.

I also think that Mark makes a good point about checking the suction and impeller for clogs. You should check your skimmer baskets, pump basket and main drain grates for debris. When you remove the pump basket, you can feel inside the impeller to check for debris.

[Gavin]

Sorry Gavin, Looks like the Hydraulics lab has kicked you to the curb even after your problem was resolved. I'll try to answer your post.

I decided to just recharge with 1lbs of DE to be on the safe side and keep pressure down. I think 1lb should be sufficient for this filter to clean the water and won't clog up the filter and back washing will work better.

The filter pressure is now 10psi.

Careful, don't think that less D.E. is better. It could be worse. Those "tubes" in the filter are not really the filter, the D.E. that coats the tubes is really the filter. If you don't get the proper amount of DE on them, then the debris can get impregnated into the mesh of the tube (because it is exposed or partially exposed), and you could wind up back here with the same problem.

Find out for certain how much DE you need for that filter and apply that much. I think i read that you have a 1 lb. scooper? Make sure it is for DE, cuz DE is a lot less dense than just about everything else.

Example: a 2 lb coffee can is about equal to 1lb of DE.

Good Luck

Thanks. I'm actually enjoying the read on hydraulics.

yes I have a DE scoop. the pool store told me to use a coffee can of DE once. but I got a scoop. I notice the Hayward people say to add more DE like 4lbs but I've heard thats way to much. I will monitor it.

[Gavin]

I think that the primary issue has been a dirty filter. Once the filter was cleaned, the pressure went down to the correct level.

Gavin, the EC-65 takes 6 pounds of DE. That is how much you should add after you disassemble the filter and clean it. After backwashing the filter, you should add the amount of DE that was lost due to backwashing.

As PC notes, the filter needs the correct amount of DE to function properly.

If you can catch the DE somehow, that can help you determine the amount lost and how much you need to add.

Most pool stores sell a one-pound DE scoop.

I also think that Mark makes a good point about checking the suction and impeller for clogs. You should check your skimmer baskets, pump basket and main drain grates for debris. When you remove the pump basket, you can feel inside the impeller to check for debris.

so maybe I actually needed to add more. Hmmm..but 6lbs is a lot and I've heard lots of people say the filter manufacturers say to add way too much DE and that clogs up the filter. I need to research some more and find out how much people are adding to EC65's. I think the pool people at the store said to just add a coffee can of DE.

[quantumchromodynamics]

For the EC65A Scoop 6 lbs. (2.7 kgs.) of diatomite into the system through the skimmer as fast as the plumbing will take it. http://www.haywardnet.com/products/Manuals...s/Manual257.pdf

The bulk density of DE is about 2.00 to 2.67 pounds per gallon. The EC-65 will take about 2.25-3.00 gallons of DE on a fresh fill.

That will create a layer on the fingers about 1/8 to 3/16-inch thick.

Bulk density of DE is about 15 to 20 pounds per cubic foot.

The problem people are having is that they are backwashing and only getting about 2 or 3 pounds of the old DE out and then adding 6 more pounds of new DE. This is what is causing excess DE buildup in the filters. You add about 6 pounds at startup and then less than 6 pounds after backwashing.

I will normally add about 4 to 6 pounds on startup and then 3 to 4 after backwashing depending on how much DE comes out.

[Gavin]

For the EC65A Scoop 6 lbs. (2.7 kgs.) of diatomite into the system through the skimmer as fast as the plumbing will take it. http://www.haywardnet.com/products/Manuals...s/Manual257.pdf

The bulk density of DE is about 2 pounds per gallon. The EC-65 will take about 3 gallons of DE on a fresh fill.

That will create a layer on the fingers about 3/16-inch thick (0.1782 inch, 4.526 mm).

Bulk density of DE is about 15 pounds per cubic foot.

The problem people are having is that they are backwashing and only getting about 2 or 3 pounds of the old DE out and then adding 6 more pounds of new DE. This is what is causing excess DE buildup in the filters. You add about 6 pounds at startup and then less than 6 pounds after backwashing.

I will normally add about 4 to 6 pounds on startup and then 3 to 4 after backwashing depending on how much DE comes out.

Thanks. is it a good idea to mix the DE in a bucket of water before pouring in the skimmer? also I only added 1 lb on start up. do I now have to open the filter back up and clean it and then add 6 lbs to start up or should I just backwash and then add like 4 lbs? Thanks