texasmax Posted November 12, 2011 Report Share Posted November 12, 2011 Installed a new DE filter last weekend, Pentair FNS Plus 60sqft. I wanted to run it completely empty, and then loaded with DE, to get two data points for how restrictive my plumbing is. After I first installed it, ran it with absolutely no DE, and saw 13psi on the filter at 65-70gpm. It actually ran like that for a week since I ran out of time So this morning, loaded it up with 6lbs of DE per specs. Specifically, mixed 3lbs with water in a Home Depot (5-10 gallon?) bucket about half full, not thick at all, and poured it through a skimmer. Waited 5 minutes, no difference in pressure or flow, did the second 3 pounds, still no difference in pressure or flow. About 2 hours later, MAYBE a half psi higher at the filter, no discernible change in flow. Is this normal? Shouldn't I expect some rise in pressure? I'm plumbed correctly, and the DE didn't go to waste (the waste side of the multiport valve isn't even hooked up yet, so any waste would be flooding the pad). Before I installed it, I opened it up to have a look, and didn't notice anything grossly out of place- though is it possible that the media isn't plumbed internally correctly? I haven't noticed any DE in the pool, but then again, I haven't looked closely until now that I realize I should be checking... Thanks for reading! Quote Link to comment Share on other sites More sharing options...
PoolGuyNJ Posted November 12, 2011 Report Share Posted November 12, 2011 Hope you backwashed before you added DE. That's pretty normal, assuming the chems are normal. Next time though, mix all the DE in one shot for a more even coating of the grids. 65 GPM is not a lot for this filter. Sounds like you have a 1 HP pump. Scott Quote Link to comment Share on other sites More sharing options...
texasmax Posted November 12, 2011 Author Report Share Posted November 12, 2011 Chemicals are in balance, and it's a brand new filter, so nothing to backwash. I had it running with empty media, no DE in there at all, until the first charge today. It's a 1.5hp (1.1sf) pump. We moved in to this house over the summer, but haven't had the time to play with it as much as I'd like to have (yet); all the individual pressure side and vacuum side lines at the pad are individually-valved, so I can experiment a bit- my guess is that the vacuum-side lines are pitifully under-sized and that's what's restricting me- especially since I'm convinced one of the two skimmer lines is clogged. My previous pool had a 2.2sfhp pump and pushed 110gpm through a 420sqft cartridge filter... but I digress, different conversation. So, then, it IS normal to not see a pressure increase from naked (no DE at all) media to properly-coated? Again, initial startup on a brand-new filter. Quote Link to comment Share on other sites More sharing options...
Bugman1400 Posted November 12, 2011 Report Share Posted November 12, 2011 Chemicals are in balance, and it's a brand new filter, so nothing to backwash. I had it running with empty media, no DE in there at all, until the first charge today. It's a 1.5hp (1.1sf) pump. We moved in to this house over the summer, but haven't had the time to play with it as much as I'd like to have (yet); all the individual pressure side and vacuum side lines at the pad are individually-valved, so I can experiment a bit- my guess is that the vacuum-side lines are pitifully under-sized and that's what's restricting me- especially since I'm convinced one of the two skimmer lines is clogged. My previous pool had a 2.2sfhp pump and pushed 110gpm through a 420sqft cartridge filter... but I digress, different conversation. So, then, it IS normal to not see a pressure increase from naked (no DE at all) media to properly-coated? Again, initial startup on a brand-new filter. I think what PoolGuy was referring to with running the filter without DE is that......you are sucking all the dirt and debris from the pool to your naked grids during the time you were getting your baseline data point. So, if you added DE after that without backwashing then your DE is now on top of your dirt and debris. I'll ask the next question.....what is the size of your plumbing? Quote Link to comment Share on other sites More sharing options...
texasmax Posted November 12, 2011 Author Report Share Posted November 12, 2011 OK- gotcha, makes sense . Yes, I didn't take my first baseline until after the naked grids were running for a week. I'll (finish my plumbing) and run the backwash for an extended period, open up the filter and make sure everything's clean, then run a baseline on the naked grids, and then another reading after the initial DE charge and see what happens. Since you asked , the pressure side is split 3 ways- 2" off to 6 or so return jets, 2" off to the spa (that overflows into the pool), and a 1.25" off to 3 quite small jets at the lower edge in the deep end (9' diving side). Suction side- 1.5" from the main drain, 1.5" from 2 skimmers (1 of which barely has any suction, to be investigated), and a 2" from the spa drain. All 6 in/out lines have their own valves, and they're all fully open except the spa drain suction which has to stay mostly closed or it drains the spa. The plumbing isn't ideal but it is what it is; I think if I figure out what's going on with the skimmer I'll free up some more flow on the suction side (not exactly sure what I'm going to do there since the 2 skimmers share 1 line coming out at the pad- possibly one of those flat drain snakes made for outside drains, or see if I can pressurize it. The pool was checked for leaks before we moved in, and none were found). Quote Link to comment Share on other sites More sharing options...
Bugman1400 Posted November 12, 2011 Report Share Posted November 12, 2011 Another question....how are you getting your flow rate? Quote Link to comment Share on other sites More sharing options...
texasmax Posted November 12, 2011 Author Report Share Posted November 12, 2011 Ive got a blue-white 2" flowmeter in place after the filter, in a long enough run for proper placement. Believe its the 150gpm max model. My pride and joy. Quote Link to comment Share on other sites More sharing options...
Bugman1400 Posted November 12, 2011 Report Share Posted November 12, 2011 Sounds like a nice toy....wish I had one. Although, they don't seem too expensive....maybe I'll get one. What is your flow rate in Recirc mode (DE filter bypassed)? Also, what is the spec'd flow rate of the pump? Quote Link to comment Share on other sites More sharing options...
texasmax Posted November 12, 2011 Author Report Share Posted November 12, 2011 Good question... in recirculate, I'm pushing 90gpm. The filter has a max flow rate of 150gpm. Quote Link to comment Share on other sites More sharing options...
texasmax Posted November 12, 2011 Author Report Share Posted November 12, 2011 Oh, you asked about the pump, will run out in a bit and check the model, think it's a WhisperFlo. Quote Link to comment Share on other sites More sharing options...
texasmax Posted November 12, 2011 Author Report Share Posted November 12, 2011 Yes, WhisperFlo WF-26. Curve shows 67.5 feet head loss @67.5gpm (filter in-line), 50 feet @90gpm (filter bypass). So the filter brings me a loss of 17.5ft, which is 7.6psi. Now the math gets fuzzy (if it isn't already). Curve for the filter shows 4psi loss @67.5gpm. Who knows what the difference between the 7.6 and 4 means, especially since I'm using a multiport valve that's got all sorts of different restrictions, from position to position. Back to the question, at 67.5gpm, based on curve G above, I'm really in the sweet spot for pump efficiency (by chance). Quote Link to comment Share on other sites More sharing options...
Bugman1400 Posted November 13, 2011 Report Share Posted November 13, 2011 Yes, WhisperFlo WF-26. Curve shows 67.5 feet head loss @67.5gpm (filter in-line), 50 feet @90gpm (filter bypass). So the filter brings me a loss of 17.5ft, which is 7.6psi. Now the math gets fuzzy (if it isn't already). Curve for the filter shows 4psi loss @67.5gpm. Who knows what the difference between the 7.6 and 4 means, especially since I'm using a multiport valve that's got all sorts of different restrictions, from position to position. Back to the question, at 67.5gpm, based on curve G above, I'm really in the sweet spot for pump efficiency (by chance). I don't think it is by chance, but by design. I think the difference between 7.6 and 4 is measurement error. For example, you indicated 50ft.@90GPM, but I read it as 48 or 49ft.@90GPM. Add up all those error rates including reading you Blue & White and you'll see why the true number is hard to calculate. Perhaps, this pump is pumping against a higher head pressure than your last pool. All in all, everything seems good. Quote Link to comment Share on other sites More sharing options...
texasmax Posted November 19, 2011 Author Report Share Posted November 19, 2011 Thanks! So here's what the grids looked like this morning- interested in all of your thoughts on the unevenness- a lot more at the top and not enough at the bottom. Does it come loose and float to the top when the pump is off? I finished up the plumbing so now I'm able to backwash. Backwashed for 3-4 minutes, and everything looks as clean as it was when it was brand new. It's about to rain here, so I'm leaving the pump off until I can get out there and get a new coating of DE on (and this time I'll mix all the DE in one bucket and pour in at once instead of in 2 batches). Based on the pic, does it help to take your time pouring it in (took about 2 minutes total the first time around). Quote Link to comment Share on other sites More sharing options...
PoolGuyNJ Posted November 20, 2011 Report Share Posted November 20, 2011 Often, some DE will let go of the grids when the pump shut off. The dirt that was captured often falls also and is the last to re-coat. This is normal and expected and desired. Pentair recommends not running a DE filter 24/7 in fact, because of this. 23/7 is the max. Scott Quote Link to comment Share on other sites More sharing options...
texasmax Posted November 20, 2011 Author Report Share Posted November 20, 2011 Thanks!!! That makes me feel much better. Quote Link to comment Share on other sites More sharing options...
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