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Built-in acrylic spa as add-on to existing pool, good idea or not?

last year
last modified: last year

Dear all, I am shopping to add a spa to my pool. I would like it to look as built-in as possible. These are the options I thought of:

  • online I found that Bullfrogspas have hot tubs that can be in-ground using Spavault ( )
  • a contractor quoted me a 78"x78" in-ground spa, in concrete (or better shotcrete), with a waterfall that connects it to the pool. Quote is 55k+ depending on options, since he said he "must cut into the shell of the pool quite a bit to tie the pool and spa together which then requires the pool to be replastered and tiled, and an engineer is needed".
  • From a different contractor I got quotes for:

a) A 7x7 foot in-ground acrylic spa, with a waterfall that connects spa to the pool. In particular, the model SW-504 sold by SpillwaySPA (The Spillway Spa Non-Spill Hot Tub Spa Collection). The quote is 26k, and it includes the acrylic spa, the Gas Heater (StaRite Max E Therm LP LOW NOX propane Gas Pool Heater 333,000 BTU #SR333LP), one Pentair pump (1.5HP UP Rated SuperFlo single speed pump 115/220V 1.5 HP), Spa footers and cut concrete for plumbing + repair deck with rough finish, Jandy IQ 904-PS automation center with two actuators and web connect, CMP Delta UV D80 CMP Ulta Violet sanitizer 100GPM Flow 2".

b) A 7x7 foot in-ground acrylic spa, with no waterfalll. In particular, the model NS-301 sold by SpillwaySPA (Spillway Spas NS-301 Hot Tub Spa for Relaxation & Hydrotherapy). The quote is 26k, and it includes the same items as the spillway quote above, except that it needs an extra pump (two instead of one). The extra pump is $800, and spillway spa costs ~$800 more than non spillway spa, so both quotes are ~26k. It seems like a no-brainer to go for the acrylic one rather than the shotcrete. The contractor said that acrylic is more comfortable than shotcrete, and cheaper because he doesn't need an engineer, they do not need to modify the pool shell, they just dig a hole next to the pool wall and put the spa partially inside it, with the waterfall at the edge as in the pictures you see on Spillwayspas website or their Instagram ( Bullfrog seems like a good option as well. I am not ruling out a standalone hot tub yet, if it can look as fancy as a built-in.

The questions I have for you guys are:

  1. I wonder if you know any model of standalone hot tubs that can be tiled or can be covered by bricks to make them look more built-in.

2) Do you agree this acrylic pool is a better choice than the concrete one, or am I missing something?

3) Do you think in-ground acrylic is better than standalone hot tub? And those 26k would also go the house value if in 8-10 years I happen to sell, while in 8-10 years a 10-15k portable hot tub is probably almost worthless. What about the Bullfrog vault? Can it be replaced when it fails in like 15 years? What about maintenance? It won't give me a spillway, but it would give me many more jets than those acrylic spas.

4) If I go for an acrylic drop-in, do you agree I should go for a spillway version rather than a separate one? I will need to just clean a single body of water. Isnt it better from a point of view of bacteria and viruses? Spillway has also the advantage of having, for the same price, a beautiful waterfall and I can also heat up my pool if I wanted for a special occasion in the winter. So it seems like 3 points in favor of spillway.

5) Is there any issue with adding the weight of the acrylic spa next to the pool? I was thinking to have it two feet or 1 and 1/2 feet off the ground. So for 2 feet and a 78"x78" spa, that would give a 84.5 cubic feet that are 5300 pounds of water. This assumes that there are 6 people inside (who weigh like water, more or less) and who make water raise to the edge. In reality, I think it should be a bit less than that, soil is dug out to make space for the piping, so most of the part under the acrylic is air. Hot tubs would probably have a similar weight.

6) If I go acrylic, how tall should I make the spa above the ground? Or should I go flush with the ground? On those Instagram pictures, you see from flush to probably 2.5 feet high. If you think the weight is a problem for the pool wall I can keep it maybe around 1 foot, which makes stepping in easier with no need for a couple of steps, the waterfall would have some decent size. A higher spa would make the waterfall nicer and more dramatic (especially if I put lights behind it)

7) That Spillwayspa acrylic tub doesn't have many jets. Any way you know of an acrylic spa with a spillway with a bunch of jets so that I can have the best of all the options?

Any other concerns? Thank you

Below an example taken from the Instagram link above for your convenience

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