Purchasing a new AG Pool. Need advice...

[Serapium]

So, despite being a newly registered user, I've been a huge fan of this site for years. I used the BBB method reliably for three years at my last house on my 15' AG pool, and loved how easy it was (and inexpensive). I never registered at that time because I was able to find all the answers I needed just from the web site itself.

Fast forward, and I've been without a pool in a new location for three years. My trusty 15' pool went with the last house. We're ready for something much larger. I'm looking at either 30' or 33' round AG, but am somewhat lost in the options. The last pool I had was a used pool when I bought it. I got it for $300 if I tore it down and moved it myself. As such, it was more of an impulse buy than anything. No thought went into filter, pump, liner, etc..... I just used what it had.

That said, to any of the pool experts here.... If you were going to buy a new pool, with all new equipment, what route would you go? Traditional BBB as recommended here, or SWCG?

Also, I know I don't want too big of a pump for my filter and have seen the equipment combination recommended elsewhere on this site, but is a single 1 HP pump really enough for a 33' pool? Would I be better off with the addition of another 1 HP pump/ skimmer to aid in circulation on the other side of the pool?

Thanks for any advice!

[Watermom]

I'm going to let someone else give you the equipment advice you are asking for. I just wanted to welcome you to the forum and let you know that you aren't being ignored! Forum has been a little slower today. Probably because everybody is celebrating Mother's Day! Hang tight. Someone will be along.

[Serapium]

Thanks for the welcome, Watermom!

Still hoping for some advice on my questions above, plus some opinions on DE filters vs sand filters. If you were buying all new, which one would you choose?

[Watermom]

I would buy a sand filter but that is just my preference. They are by far the easiest to maintain. However, you will find just as many people who will tell you to buy a DE filter or a a cartridge filter. DE filters provide the best filtration. However, I have never had any issues with my sand filter not filtering well in all the years I have had a pool. All of the moderators on this forum have sand filters, too. My opinion is that I wouldn't want a cartridge filter because of the hassle of cleaning them. But, some of our members love theirs.

An SWCG does allow for less frequent "fooling with" your pool BUT most AG pool warranties are voided if you add an SWCG.

Others will chime in with their opinions, I'm sure. Hope this helps maybe a little.

[Serapium]

Definitely helps! Bonus is that I'm already familiar with sand filters. How about the pump question? I know I don't want to overpower the filter with too big of a pump, and in my 15' AG pool my 1 HP pump was more than enough to circulate water through the whole pool. A 33' pool is a much different monster. I know I'll have to run the pump much more often to achieve enough water turnover through the pump, but will a 1 HP pump even move enough water for adequate circulation all the way to the other side of the pool?

[PoolDoc]

A 1HP inground pump is MORE than enough for your pool: a 33' x 52" pool only holds around 22,000 gallons. Optimal MAXIMUM circulation is around 60 GPM, but you probably want more like 48 GPM.

A combination like this:

Hayward S244S Pro-Series 24-Inch Side-Mount 1-1/2-Inch Vari-Flo Valve Pool Filter (http://www.amazon.com/exec/obidos/ASIN/B000P5C602/poolbooks) @ Amazon
Hayward Super Pump 2-speed 230V w/Switch (http://www.a1poolparts.com/-strse-842/Hayward-Super-Pump-2-dsh-speed/Detail.bok) @ A1PoolParts
would work exceptionally well and be very efficient to operate. You would leave the pump on low speed except when vacuuming, backwashing, or cleaning up, and you would definitely want the smaller pump!

But, I'm not sure if you are planning to use an IG pump and filter.

[aylad]

If you're talking about 33' round, depth 48", then you're looking at about 25,600 gallons, which is roughly the same volume as my pool (mine is 18 x 36 rectangle). I have a 1 HP pump and 300# sand filter, and it works just fine for me.

[PoolDoc]

If you're talking about 33' round, depth 48", then you're looking at about 25,600 gallons.

??
radius squared x pi x depth x gal/cft
15.5*15.5*3.14*4*7.48=22,571

[aylad]

bleachcalc volume calculation......

Janet

[PoolDoc]

Another error, in it then.

[BigDave]

??
radius squared x pi x depth x gal/cft
15.5*15.5*3.14*4*7.48=22,571

I'm so sorry to contradict, but I must respectfully point out that half of 33 is 16.5 and that (33/2)^2*Pi*4*7.48=25590.534.
15.5 is the gallons in a half-barrel. Is it the weekend yet?

[Serapium]

Thanks for the input! I know that a 1HP pump is capable of circulating enough water to filter the volume of the pool... I guess what I'm actually wondering is if the filtered H2O coming out the return to the pool comes out with enough force to circulate water evenly throughout the entire pool. In other words, with a 1HP pump turning over 30K gallons a day, are you really filtering 30K gallons, or are you filtering 10K gallons three times?

[PoolDoc]

@ Janet, Dave: my bad! sorry! (thanks for the correction!)

@ Serapium: what actually happens when you circulate water is mind-numbingly complex, but roughly you can think of it like this:

UP: unfiltered water in pool
CP: clean filtered water in pool
UF: unfiltered water in pipes
CF: clean filtered water in pipes

1. Initially, the system pulls UP into the pipes, pushes UF through the filter and discharges CF into the pool.

2. But, now the pool contains UP + a small amount of CP. There's a lag in mixing -- how much lag depends on the way the pool returns and drains are arranged. But anyhow for the next few minutes, the system continues to pull ONLY UP from the pool, and return only CF to the pool.

3. But, then, the system begins to pull a mix of UP and CP into the system, so the filter NOW is filtering water that is mostly UP, but contains a little CP. CP has ALREADY been filtered, so that's pretty much wasted effort.

4. As time goes on, the system pulls an ever decreasing amount of UP into the pipes and more and more CP, wasting more and more of the filtration by filtering a mix of UF and CF.

So, even though a 100GPM system can filter a volume of water EQUIVALENT to the volume in the pool, in only 1.7 hours, it will take MUCH longer than -- probably at least 10 cycles before 99% of the water in the pool has been filtered 1 time.

For a typical pool with side inlets, a main drain, and skimmers and an 8 hour turnover rate, it will take around 3 days to filter 99% of the water. Commercial pools, with laminar flow floor inlets and primary circulation through skim gutters can accomplish the same task in just one day. And, I've actually worked with one pool with this design: it was MUCH faster to clean up, then pools with more typical piping systems.

[Serapium]

Thanks, Ben! So, I've then come full circle back to one of my original questions at the beginning of this post :)

"... is a single 1 HP pump really enough for a 33' pool? Would I be better off with the addition of another 1 HP pump/ skimmer to aid in circulation on the other side of the pool?"

Your thoughts? It seems that the addition of another pump on the opposite side of the pool to aid in water circulation would make the beginning of the efficiency progression you laid out even LESS efficient, as you would likely have a higher proportion of C.P. to U.P. at the beginning of the cycle. However, if the pumps were only going to run for.... say... eight hours a day, would the addition of the second pump not increase the overall efficiency of the system when looked at from a macro scale? What if you were to run both pumps for two hours at a shot on a timer spaced out through five segments of the day? Seems to me that over time you would filter more U.P. in less than half the time (hence using less energy) than if you didn't have the second pump. It's been years since I've tried to do the calculus involved in that kind of computation so I'm a little rusty, but I think I'm running under correct assumptions. In my old 15' pool this wasn't really an issue since the C.P. returned to the pool caused distinct circulation within the overall vessel, but I don't think that is going to be likely given the fluid mechanics involved with the change from a 5,300 gallon vessel to a nearly 28,000 gallon vessel.

[PoolDoc]

Running far behind on forum questions now, so I'm gonna be brief:

Yes, a 1HP pump, especially in the combination I laid out for you, will perform very well. If you want to OPTIMIZE performance, putting 2 - 3 inlets on sides of the pool OPPOSITE the skimmer, using larger orifices on the eyeballs, and putting 1 of the inlets LOW and close to the floor, will help accomplish that goal.

[Serapium]

Ah, I see! Thanks!