Want 2 bld giant in ground hot-tub/spa on existing pool with spill over. OPINIONS!!!

[ionizer]

Hi everyone. So we have a 32,000 gallon free form pool. See image:
View attachment 69182

The landscaped area in red has 3 spouts for waterfalls embedded in the rock that go into the pool. I want to completely remove the landscaped area and add an inground hot tub/spa. However, I don't want some dinky 6 person round seater and because my pool is free-form, I don't want some giant rectangle sitting next to it - it would be awkward.

A few pool builders have suggested simply building a "mini pool" and putting a vinyl liner on it, building seats and putting in jets. I don't anticipate keeping the water at 105 degrees all the time, if ever, but more or less use it as a "warmer area" to be in an extra month or two before normal pool season here in NJ And perhaps another 1-1.5 months at the end of the season.

My question is this:
(1) Are there any "Drop-in" prefabricated units that would be appropriate for this area that are larger?
(2) Is using a vinyl liner for this idea ok? Obviously you don't really see too many vinyl liner hot-tubs... i assume there is a reason, but given my circumstances, would it be acceptable? Will I face any issues?
(3) Noting that my pool equipment is basically in the top right (you cant see it, but its under the trees in the top right) and thus lines will obviously have to be dug, but not insanely far - what are some ballparks you might expect this job to cost? Is $10k possible? Is $15k? Am I looking at $30k minimum?
(4) I've seen some people, especially the guy from texas, embed nice small water slides as part of the rock aesthetics. I was thinking of a small slide that starts on the right hand side of the to be built hot tub/spa, wraps around slightly and then goes into the bottom portion of the pool which is the deep end. Any thoughts on that?

Basically looking for opinions on whether this is a
(A) "sure anything can be done for a price" type project
VS
(B) "yeah, i've seen people do this before. It's not $5k, but you could do it right for $10-$15k"

and
(C) Vinyl hot tub? No way you are crazy
VS
(D) Yeah i've seen people build mini-like pools that were giant hot tubs and use vinyl before.

....I welcome all thoughts, criticisms and feedback openly! Thank you!

 

[JoyfulNoise]

How large is that area?

One thing to consider would be water volume and heater capacity. The largest residential natural gas heater you can get for a pool is typically about 400,000 BTUs/hr. Even in a small round attached spa that holds approximately 650 gallons of water, you're looking at 20-30mins to get the tub up to temperature. With a heat pump, more like 60-90mins. A few thousand gallons of water, even with the largest sized heater, will take a hours to heat up to heat up. Allowing it to cool down will just be a huge waste of money as cycling a heater costs more than just trying to maintain a warm body of water. Since it will be inground, there will be a big loss of heat through conduction if the pool wall is not insulated from the ground in some way.

 

[ionizer]

How large is that area?

One thing to consider would be water volume and heater capacity. The largest residential natural gas heater you can get for a pool is typically about 400,000 BTUs/hr. Even in a small round attached spa that holds approximately 650 gallons of water, you're looking at 20-30mins to get the tub up to temperature. With a heat pump, more like 60-90mins. A few thousand gallons of water, even with the largest sized heater, will take a hours to heat up to heat up. Allowing it to cool down will just be a huge waste of money as cycling a heater costs more than just trying to maintain a warm body of water. Since it will be inground, there will be a big loss of heat through conduction if the pool wall is not insulated from the ground in some way.

I'll get some measurements, but using google maps to measure from longest end to end it is 28ft by 13 ft. However, the actual inground spa would have to be smaller (1) to account for rocks to set the scene as well as coping between the hot tub and the pool.

My current heater is shot. Was the original from the prior owner and from 2001. So I was due for a new heater, and certainly would have to probably get the larger ones. But rushing to heat isnt necessarily a concern. I consider 30 minutes fast....but are you saying with the spillover function that it takes hours for just the spa to heat up because its cycling the water into the pool? I assumed it would lose some water, but still maintain most of it in the hot tub area and thus heat up faster and not uniformally with the rest of the pool. Not sure if evident in the picture, but we have really no trees, so we get full sun.

As for insulation, I guess it should be insulated as much as pre-fab would be...it actually might be higher than the ground though b/c the point is to elevate it a little above the pool in order to get the spillover effect and potential water slide.

any other concerns/thoughts? what about the vinyl liner being used in a hot tub?

 

[JoyfulNoise]

The way the automation and plumbing setups would work is that, in "SPA mode", you would only be recirculating water in the spa itself (taking water from the spa, filter/heat/chlorinate and return it to the spa through the jets). If you were to pull water from the pool and then try to heat that and return it to the spa only to spillover into the pool again, then you're heating both volumes of water.

As for vinyl....hmmmm, doesn't sound like a good idea to me. But, if you definitely had to go the route of a small vinyl pool, then I'd say go for composite (polymer) walls with a good vermiculite base and then the thickest possible liner material you could get. Perhaps the spillway from the spa-pool into the main pool could be less of spillover and more of a cascading rock-filled "river". Since this would be a heated spa-pool, maybe even doing floor bubblers/jets would had a nice effect along with a couple of dedicated "therapy benches" and then just some plain old seating spots. Heck, go all out and throw in a "floating" table and some submerged bar stools....with the sunken bar attached to one side so you can serve drinks....

...we have no problem spending other people's money around here.

 

[jimim]

I'm in pa. My builder likes to do the following and I along with many other close friends who worked on project agree with the following.

We close here cause of winter. Same as you. So not a lot of use. He said he likes to always do his spas as separate isolated systems so they can run longer. So separate equipment.

He inly uses fiberglass even on hos gunite pools if above is followed to try and keep price and ease down. He is very comfortable working with them when he does hem as overflow into only pools. They hold up and they have never had a winter issue cause they aren't huge.

I said ok separate but I want it to look built into pool overflow and all. Obviously you can't do that for winter use if main pool is closed. That's where gunite comes in. He has done some pretty funky gunite ones tht are infinity edge raised to look like they flow into the pool. All he does is. Hold a nice boulder or raised beams at the pool. Places spa higher and infinity edges the spa near the pool. It's pretty wicked. He did a job that he did the infinity edge to the pool as stools to the raised pool beam to sit and drink and look into pool. They were sitting in the spa overflow. That was cool.

All on all he likes to keep it simple. Separate system fiberglass unit raised sitting behind pool surround by landscaping or rock to give the look but no overflow bit if ocerflow is wanted then he starts spending money and goes gunite with infinity edge idea above. In my set up if we ever add I will do the later. Raised hide it behind pool with no overflow or infinity edge but make it as natural as possible. The overflow is nice but it's in he end smoke and mirrors that doesn't get much use in our area so keep it separate and then you get a ton of use out of it!

but u would be safe with fiber in our area. No vinyl. I actually just texted him.

 

[Sandissimos]

Hello from England!
When we had our pool built we were told not to run the heater any higher than 26°C because high temperatures are not good for vinyl liners. As we wanted our liner to last as long as possible we capped our heater at that temperature. I'm not sure what the effects of a super-heated pool would be, but presumably it would cut short the life of the liner.

- - - Updated - - -

 

[ionizer]

The way the automation and plumbing setups would work is that, in "SPA mode", you would only be recirculating water in the spa itself (taking water from the spa, filter/heat/chlorinate and return it to the spa through the jets). If you were to pull water from the pool and then try to heat that and return it to the spa only to spillover into the pool again, then you're heating both volumes of water.

As for vinyl....hmmmm, doesn't sound like a good idea to me. But, if you definitely had to go the route of a small vinyl pool, then I'd say go for composite (polymer) walls with a good vermiculite base and then the thickest possible liner material you could get. Perhaps the spillway from the spa-pool into the main pool could be less of spillover and more of a cascading rock-filled "river". Since this would be a heated spa-pool, maybe even doing floor bubblers/jets would had a nice effect along with a couple of dedicated "therapy benches" and then just some plain old seating spots. Heck, go all out and throw in a "floating" table and some submerged bar stools....with the sunken bar attached to one side so you can serve drinks....

...we have no problem spending other people's money around here.

yeah, it was stated we'd use the 27mill for the liner if we did it.
so if i am in spa mode, doesn't the water still spill over into the pool?
i like the rock-filled river or waterfall like stuff, my only concern is the rocks we have now get dirty - i guess if water is always running down it, it remains cleaner? our waterfall today is just 3 spouts out of a specific area, that don't hit the remainder of the rocks.
not sure how much the seating adds to the cost, but contemplating it.
dont know what a "floating" table" is.
sunken bar is probably going out of budget

what do you think the range "withing the realistic scope" is? 10k? 15k? 20k? 25k? 35k? 50k+?

- - - Updated - - -

I'm in pa. My builder likes to do the following and I along with many other close friends who worked on project agree with the following.

We close here cause of winter. Same as you. So not a lot of use. He said he likes to always do his spas as separate isolated systems so they can run longer. So separate equipment.

He inly uses fiberglass even on hos gunite pools if above is followed to try and keep price and ease down. He is very comfortable working with them when he does hem as overflow into only pools. They hold up and they have never had a winter issue cause they aren't huge.

I said ok separate but I want it to look built into pool overflow and all. Obviously you can't do that for winter use if main pool is closed. That's where gunite comes in. He has done some pretty funky gunite ones tht are infinity edge raised to look like they flow into the pool. All he does is. Hold a nice boulder or raised beams at the pool. Places spa higher and infinity edges the spa near the pool. It's pretty wicked. He did a job that he did the infinity edge to the pool as stools to the raised pool beam to sit and drink and look into pool. They were sitting in the spa overflow. That was cool.

All on all he likes to keep it simple. Separate system fiberglass unit raised sitting behind pool surround by landscaping or rock to give the look but no overflow bit if ocerflow is wanted then he starts spending money and goes gunite with infinity edge idea above. In my set up if we ever add I will do the later. Raised hide it behind pool with no overflow or infinity edge but make it as natural as possible. The overflow is nice but it's in he end smoke and mirrors that doesn't get much use in our area so keep it separate and then you get a ton of use out of it!

but u would be safe with fiber in our area. No vinyl. I actually just texted him.

thanks for the feedback.
reasons i am against the separate unit are a number of reasons:
(1) I don't want to test two separate water systems and maintain them separately. i want to treat one water system and only one water system
(2) I don't want to "open the spa" and then later "open the pool"
(3) I'd like a slide from the spa (or around the back of it into the pool...ideally using flow of water from one to the other
(4) I do want a small portion of the heater spa water to flow into the pool to warm it a little bit, even if it is less so.

- - - Updated - - -

Hello from England!
When we had our pool built we were told not to run the heater any higher than 26°C because high temperatures are not good for vinyl liners. As we wanted our liner to last as long as possible we capped our heater at that temperature. I'm not sure what the effects of a super-heated pool would be, but presumably it would cut short the life of the liner.

- - - Updated - - -

hello g'uv'nuh

26 degrees C can't be right. That is 78.8 F. And I can tell you, in a warm summer my pool can get to 78.8 naturally from the air. So I have to imagine most people who ever heat a pool do so and bring it up in the 80s (26.67-31.67 Celsius) ...and those are normal vinyl lined pools. maybe they told you a different #?