Plumbing auto-fill at pad... where to tap in?

[rtilghman]

Wrapping up our pool project (Austin, TX) and have decided to add in an auto-fill. Didn't want to pay the upgrade initially, but doing some research I've discovered the better option (to me) of plumbing it at the pad. Will likely make it manual at first, but I'm planning to eventually add in a wireless monitor (awesome!).

The issue I'm having is the best place to cut into the lines...?

I've found a few threads here and on other forums that conclude it's best to do it after the pump, which makes sense to avoid pressurizing the inlet side and potentially pushing back on the skimmers. However, beyond that there doesn't seem to be any consensus or recommendations... after/before the filter? The UV/chlorinator? The heater?

To provide some context, I have a pool/spa hybrid with a single heater (automated switchover). Looks something like this:

Inlet : Pump : Filter (large) : UV/Chlorinator : Heater : Return



If you look at the picture you can see a spigot off the Pump -> Filter line that seems like a perfect spot (cut into that close to the spigot end). However it occurred to me that a normal auto-fill wouldn't go through the equipment at all... it would empty into the pool. This seems to imply I should put it after all the equipment (return)? But wouldn't it make to put it forward and "clean/chlorinate" the fill water (city water, already fairly clean) if I can? If I do put it behind the filters, do I put it ahead of the heater? Wouldn't it be advantageous to potentially (colder weather) heat any water I return?

Thanks in advance for any help, not really sure what the implications of different approaches are and if there's a best place to put it.

Rick

 

[zethacat]

I always thought that sort of thing was done in the skimmer itself. I have an underground line running from my hose bib to the closest skimmer.

 

[JayBauman]

If I understand you correctly, you want to put an autofill into your filter loop. Do you really mean auto fill (with a float valve similar to toilet valve) or just a plumbed-in way to add water to your pool?

Either way, I have to ask "is this is a good idea?". Due to pump head and pressure drop across your filter, you'll have some degree of absolute positive pressure that you'll have to be able to pump against. Do you have enough head in home water to overcome this? You'll also need a back flow prevention device to keep pool water out of your home water, which will add even greater head for you to pump against. In most municipalities, the water delivery pressure can be as low as 20psi.

In my pool, I have an auto fill sump with a float valve that puts water directly into my pool through a return jet in the wall. The only head I have to pump against is the ~12" of distance between the autofill return and the top of my pool water.

 

[jblizzle]

A normal auto-fill is not added at the pad. They are added in a skimmer like bucket near the pool with a pipe connecting the bucket and the pool. Then a float valve is used to regulate the water height.

Sounds like you are talking about a way to add water manually into your pool plumbing or eventually add a timer / sensor to control a valve to add water. I agree with Jay that I am not sure this is a good idea or even allowed by code. If you connect your freshwater source to your pool plumbing, you are one valve failure away from contaminating your freshwater supply with the pressurized pool water. (Although usually the freshwater supply should be at high pressure than the pool pump would generate).

 

[dumbcluck]

First you would need a source for the water to come from. Ideally a hose bib or water line nearby. 3/4" at least. Of course the hose bib on your equipment is only for water that's already in the system so not sure why you mention it unless you were thinking somehow of running a hose to it and running water backwards into the system which would not be a good idea.
Do you have access to pool walls?
In mine I just ran a pipe from a water line with ball valve into a hole in side of pool for fill water. Basically an underground hose.

 

[rtilghman]

Thanks for all the replies! Apologies on the terminology mix-up, I should have been a little more clear on the set-up.

What I'm doing is adding fill capabilities at the pad (into my plumbing). While it's not a traditional "auto-fill" (toilet set-up), the concept is the same since I'll be doing this "automatically" in the future via a wireless sensor that detects variances in level and adds water as appropriate.

The set-up (which I didn't document) will include a ball tap, double backflow preventer, and then hook ups. Eventually it'll include an irrigation valve and all the associated parts needed to drive an auto-filling system).

To address some key points, both those raised and not raised:

- My pressure isn't a problem. I have 65-70 PSI off the main line, which is well over what I'll be running through the pool plumbing.
- The water source will be my irrigation mainline. That line already has it's own double backflow preventer (100'+ back), which means there's no chance of contamination (the system is completely isolated from the house/drinking supply) even if the pressure fails.
- I'm not worried about a power outage since I'll never have a situation where the power is out for a long enough period of time for my pool to lose that much water. Even if that DID happen, it has a bottom pipe out of the skimmer to prevent "no water in skimmer" scenarios (I could go over a week in 100+ temps and not have a problem.

While the solution isn't without risk (the valve could get stuck open and overfill the pool, etc.), I don't think the risks are any higher than I'd run with other types of auto-fill systems. Anyway, my pool guy (who is very familiar with local codes and has built a LOT of pools) hasn't expressed any concerns (talked about it with him in detail today). He agreed with my idea that the best place is right after the pump (on that large main with the spigot). However, I'm a cautious guy, and I just wanted to see if anyone has any thoughts or experience with injecting water into the plumbing in different spots.

Thanks again for the help and insights, much appreciated.

Rick

- - - Updated - - -

First you would need a source for the water to come from. Ideally a hose bib or water line nearby. 3/4" at least. Of course the hose bib on your equipment is only for water that's already in the system so not sure why you mention it unless you were thinking somehow of running a hose to it and running water backwards into the system which would not be a good idea.
Do you have access to pool walls?
In mine I just ran a pipe from a water line with ball valve into a hole in side of pool for fill water. Basically an underground hose.

When we opened up the ground and put in the pool I overhauled a lot of my irrigation system, including the mainlines. As part of that I ran a 3/4" line to the pad, branching it underground to two heads: one for a spigot I'm going to put over there (I don't have one on that side of the house, which is VERY annoying) and the other for a dedicated line for the filling system.

If you look in the picture you can see the two capped lines on the right side (stubs near the retaining wall).

rt

 

[gwegan]

I've never seen or even heard of an auto fill at the pad. My auto fill (in the pool) has its valves and back flow preventer at the pad but that is only because my sprinkler values were there.

While I think that the best place for a drain valve is between the pump and the filter, I believe this is a poor location for inserting water into the system. You will be inserting water at the location where the pressure in the system is highest and you want to keep it that way. You are going to to filter water that doesn't need filtering.

If I was adding a inlet I would add it to a return. That would be just closest to adding it directly into the pool which is the accepted method.

 

[rtilghman]

I've never seen or even heard of an auto fill at the pad. My auto fill (in the pool) has its valves and back flow preventer at the pad but that is only because my sprinkler values were there.

While I think that the best place for a drain valve is between the pump and the filter, I believe this is a poor location for inserting water into the system. You will be inserting water at the location where the pressure in the system is highest and you want to keep it that way. You are going to to filter water that doesn't need filtering.

If I was adding a inlet I would add it to a return. That would be just closest to adding it directly into the pool which is the accepted method.

Great points. I've actually found a lot of posts online about it, but it definitely isn't as prevalent as a standard line/auto-fill into the pool. Not sure why... aside from being less costly and easier to maintain, the benefit of not having a seldom used water line to the pool seems a lot more sanitary. The fewer pipes the better IMHO.

In terms of the location, The advantage of adding it near the drain valve is that the PVC is easy to remove... I can just unscrew it from the filter/valve to simplify adding in the T. The UV/chlorinator to heater line is similar. If I want to add it to a return line (post all equipment) it means the middle of those three PVC lines running into the ground on the left side (or maybe the left one, which is the spa return since it overflows into the pool) which I will then have to pry and flex to fit the T in (assuming I don't use a pressure fitting, which I like to avoid due to pressure/failure concerns).

To your comment, it sounds like the concern with adding it "in" the equipment is around a loss of pressure in the system, but I won't be losing pressure... if anything I'd be increasing it; the check valve will eliminate any pressure loss, and at moments when the system is injecting water (likely infrequently) it'll increase the pressure slightly. Does that change your analysis or am I missing something?

Thanks,
Rick

 

[jblizzle]

Slight tangent ...

Have you have been informed (or learned from reading the forum) that we do not recommend the use of trichlor tablets for primary sanitation (especially in locations that do not close for the winter and may have water restrictions)? Additionally that UV systems serve no useful purpose in outdoor residential pools?

... End tangent.

 

[rtilghman]

Slight tangent ...

Have you have been informed (or learned from reading the forum) that we do not recommend the use of trichlor tablets for primary sanitation (especially in locations that do not close for the winter and may have water restrictions)? Additionally that UV systems serve no useful purpose in outdoor residential pools?

... End tangent.

I'm fine with tangents.

No, you're well beyond my expertise... to be honest I haven't had the time to micro-manage my pool tech, and have trusted the PB with some of the specifics.

That said, we decided against SWG due to our metal roof and plants/grass, neither of which would have survived a SWG pool given the evaporation we see here in Austin. For those who don't know (and may read this later, like I did previously), with an SWG pool salt gets deposited on nearby surfaces during evoperative cycles. If you do have a metal roof or grass and plants, the salt can quickly kill/corrode it. We also just don't mind chlorine (I kind of like it), and the lower chlorine with the UV system sounded like a nice balance.

On that note, from what I've read since then it sounds like UV systems, while not silver bullets, definitely help with giardia and other pathogens, and provide concentrated UV exposure to pool water beyond the top 2' or so (which is about as far as UV from the sun is effective) while enabling you to run lower chlorine levels. What's the basis for the conclusion that UV serves no purpose in an outdoor pool...?

With Trichlor, you have moved totally beyond my level of knowledge... I didn't even know I had Trichlor. I'll have to look into it, though a couple of the forum posts I read seemed to indicate it's fine as long as you monitor and manage your PH levels.

Either way, thanks for the insights. Clearly I have a lot to learn as we look to bring our pool online!

Rick

 

[Killer95Stang]

I'm fine with tangents.

No, you're well beyond my expertise... to be honest I haven't had the time to micro-manage my pool tech, and have trusted the PB with some of the specifics.

That said, we decided against SWG due to our metal roof and plants/grass, neither of which would have survived a SWG pool given the evaporation we see here in Austin. For those who don't know (and may read this later, like I did previously), with an SWG pool salt gets deposited on nearby surfaces during evoperative cycles. If you do have a metal roof or grass and plants, the salt can quickly kill/corrode it. We also just don't mind chlorine (I kind of like it), and the lower chlorine with the UV system sounded like a nice balance.

On that note, from what I've read since then it sounds like UV systems, while not silver bullets, definitely help with giardia and other pathogens, and provide concentrated UV exposure to pool water beyond the top 2' or so (which is about as far as UV from the sun is effective) while enabling you to run lower chlorine levels. What's the basis for the conclusion that UV serves no purpose in an outdoor pool...?

With Trichlor, you have moved totally beyond my level of knowledge... I didn't even know I had Trichlor. I'll have to look into it, though a couple of the forum posts I read seemed to indicate it's fine as long as you monitor and manage your PH levels.

Either way, thanks for the insights. Clearly I have a lot to learn as we look to bring our pool online!

Rick

 

[zethacat]

Some notes:

-- SWG pools are chlorine pools, too.

-- UV doesn't actually kill anything nor does it save you money; chlorine is still doing all the sanitizing.

--With Trichlor you need to monitor your CYA as well because the higher it gets, the more chlorine you need to use. The only way to lower CYA is to drain the pool.

--Don't ever ask someone in the pool store for advice

 

[rtilghman]

Some notes:

-- SWG pools are chlorine pools, too.

-- UV doesn't actually kill anything nor does it save you money; chlorine is still doing all the sanitizing.

--With Trichlor you need to monitor your CYA as well because the higher it gets, the more chlorine you need to use. The only way to lower CYA is to drain the pool.

--Don't ever ask someone in the pool store for advice

Great points, I didn't even know what CYA was until the previous post made me look it up... and I'm still not totally sure I get it.

So is there no way to bring your CYA down without refilling the pool? I'm actually new to Austin and the whole "never closing your pool" idea (I grew up in the NE, where closing our pool was just an annual ritual). The bleach/liquid chlorine thread sounded interesting, though I have to admit I'm a little intimidated by the idea... Trichlor tablets seem so easy/foolproof...

And on the original topic, if anyone else has thoughts on where to add water at the pad I'd love any additional guidance or insights. Leaning towards doing it near the drain **** just for simplicity, but the points about doing it after the equipment make sense.

Thanks,
Rick

 

[zethacat]

Trichlor tablets seem so easy/foolproof...

You've got it backwards, man. Bleach and liquid chlorine are the easy/foolproof methods. Trichlor tablets are the opposite. Each tablet of Trichlor adds CYA to your pool, which in return requires you to maintain a higher level of chlorine in order to properly sanitize your pool. If you don't continue to maintain the higher level of chlorine, you will have algae. An inherent problem to this is that you will not be able to get an accurate PH reading once your chlorine level is 10ppm or more. Therefore, when you get to that point it is highly recommended that you drain and refill to get rid of the CYA and start over. When you lived in the NE this wasn't an issue. Your pool was closed for most of the year and you drained it after the short pool season which took care of the problem. However, if you do not plan on closing your pool, or using it for more than 3 or 4 months of the year, you will need to deal with this issue on a regular basis if you use the Trichlor tabs.

From Pool School:

CYA - Cyanuric Acid

Cyanuric acid, often called stabilizer or conditioner, both protects FC from sunlight and lowers the effective strength of the FC (by holding some of the FC in reserve). The higher your CYA level, the more FC you need to use to get the same effect. It is important to know your CYA level so you can figure out what FC level to aim for. If you don't have a SWG or problems from extremely high amounts of sunlight, CYA is typically kept between 30 and 50. If you have a SWG or very high levels of direct sunlight, CYA is typically kept between 70 and 80.

You increase CYA by adding cyanuric acid, often sold as stabilizer or conditioner. CYA is available as a solid and as a liquid. The liquid costs a lot more, and generally isn't worth the extra expense. Solid stabilizer can take up to a week to fully register on the test, so don't retest your CYA level for a week after adding some. Solid stabilizer is best added by placing it in a sock in the skimmer basket. The pump should be run for 24 hours after adding solid stabilizer and you should avoid backwashing/cleaning the filter for a week.

In nearly all cases the best way to lower CYA is to replace water. If replacement water is extremely expensive you might want to look into a reverse osmosis water treatment.

 

[pwrstrk]

Take a look at these articles in Pool School.
ABC'S Of Pool Water Chemistry
How To Chlorinate Your Pool
And to keep everything in range you'll need one of these Test Kits. ?

 

[kimkats]

ALL of the above will help you SO much! If you read the links and take to heart the advise your pool WILL be a Trouble Free Pool.

The best things you can do to take full control of your pool is get a GOOD test kit. Look in my siggy for the link to compare them.

Kim

 

[jblizzle]

Responses is red below.

I'm fine with tangents.

No, you're well beyond my expertise... to be honest I haven't had the time to micro-manage my pool tech, and have trusted the PB with some of the specifics.

That said, we decided against SWG due to our metal roof and plants/grass, neither of which would have survived a SWG pool given the evaporation we see here in Austin. For those who don't know (and may read this later, like I did previously), with an SWG pool salt gets deposited on nearby surfaces during evoperative cycles. If you do have a metal roof or grass and plants, the salt can quickly kill/corrode it.
Salt does not evaporate it is left in the pool when the water evaporates. Any water splashed out onto surrounding surfaces can leave salt behind after the water evaporates, but salt will not get on the roof unless you are doing massive cannonballs.

We also just don't mind chlorine (I kind of like it), and the lower chlorine with the UV system sounded like a nice balance.
You can not maintain lower FC levels just because you have UV. The level of required FC is a function of your CYA level. In fact, the UV will breakdown some of the chlorine and thus require you to actually have to add more to maintain enough.

On that note, from what I've read since then it sounds like UV systems, while not silver bullets, definitely help with giardia and other pathogens, and provide concentrated UV exposure to pool water beyond the top 2' or so (which is about as far as UV from the sun is effective) while enabling you to run lower chlorine levels. What's the basis for the conclusion that UV serves no purpose in an outdoor pool...?
I am not sure of the 2' fact that you are claiming, but even if true it does not matter because the water is circulating. Again, you can not lower the FC levels as it is a function of your CYA level.

With Trichlor, you have moved totally beyond my level of knowledge... I didn't even know I had Trichlor. I'll have to look into it, though a couple of the forum posts I read seemed to indicate it's fine as long as you monitor and manage your PH levels.
The CYA build-up from the trichlor is usually the big problem and not the pH drop. Unfortunately, most of the pool industry does not acknowledge or understand the FC/CYA relationship. So if you have been getting your information from the salesman, you likely did not get scientific facts.

Either way, thanks for the insights. Clearly I have a lot to learn as we look to bring our pool online!

Rick

 

[rtilghman]

Thanks for the follow-up. Couple quick comments:

Salt does not evaporate it is left in the pool when the water evaporates. Any water splashed out onto surrounding surfaces can leave salt behind after the water evaporates, but salt will not get on the roof unless you are doing massive cannonballs.

FYI, this is actually not true. Evaporated water can and does carry trace amounts of salts and other minerals, and this content is even higher when you're talking about wind-born water (like on a sea front). This is the reason that steel roofing (and building materials) are not recommended up to 5 miles inland from a salt-water source (sea, ocean, etc.) It's also why a number of folks who install SWG (at least folks I've found) run into problems if they have a metal roof and/or sensitive plantings and grasses near the pool. It doesn't take much salt (especially accumulated over a long period) to eat steel alive (the effects on aluminum aren't much happier, but at least it doesn't outright corrode).

The reason fresh water sources have such low concentrations is because of filtering that happens as it enters the groundwater table (earth, sedimentary rock, etc.) Add this to the impact it would have on my stone deck (limestone), the corrosive aspects of the water to the equipment generally, and the higher cost of an SWG install and it just wasn't worth it to us.

You can not maintain lower FC levels just because you have UV. The level of required FC is a function of your CYA level. In fact, the UV will breakdown some of the chlorine and thus require you to actually have to add more to maintain enough.

Don't really disagree (don't know enough to say either way), I was just commenting that the stuff I found/read didn't indicate UV is worthless outdoor, was wondering if there was something (primary source) I could read on it.

I am not sure of the 2' fact that you are claiming, but even if true it does not matter because the water is circulating. Again, you can not lower the FC levels as it is a function of your CYA level.

Sure, makes total sense on CYA as I learn more. As for the 2' thing, it's one of the reasons bacteria and microbes can survive in natural water sources.

The CYA build-up from the trichlor is usually the big problem and not the pH drop. Unfortunately, most of the pool industry does not acknowledge or understand the FC/CYA relationship. So if you have been getting your information from the salesman, you likely did not get scientific facts.

Actually, the "forum posts" I mentioned were in troublefreepool.com. Completely agree on the problem you highlight, sounds like I'll have to think through my chlorine solution in more detail... along with a host of other things I have to learn about year-round pool maintenance.

Thanks again for all the insights!

-rt

 

[jblizzle]

Sea spray is a completely different mechanism for getting salt on a metal roof than evaporation. Can you point to a source that discusses salt "evaporating" with the water? I think by definition, that is not possible.

 

[JasonLion]

If you have a cartridge or DE filter you don't want to add a fill line after the filter unless you also have a check valve between the fill line and the filter, as it will tend to force dirt backwards out of the filter and back into the pool when the pump is off. A sand filter doesn't have this issue.

Salt does not evaporate. It can become airborne through splashing (or ocean waves). In practice, a salt pool in a very dry climate does pose a very slight risk to metals and plants within a few feet of the water, but it is exceedingly unlikely that it would ever get up on a roof (which would require on-going ridiculous levels of splashing combined with favorable wind conditions). In climates with almost any significant rainfall this is not an issue, as the rain will wash away any salt that does manage to accumulate.

UV can help with a few relatively rare contaminates, but these are generally only an issue in public pools. In a typical residential pool UV does essentially nothing as even minimal chlorine levels take care of everything at all common before UV has time to affect things. The only real exception is if you are having a large pool party, and even then does not make a significant difference unless you are having a large pool party two or more days in a row. UV does not allow the use of lower FC levels in a residential pool, though it can do that in a commercial/public pool.