Plan for full water exchange using tarp

Dtrav118

Member
Sep 16, 2020
23
Easton, CT
Hi everyone,

I have been struggling with metal staining all year in my first year of pool ownership and at the advice of many I have decided to do a full water exchange as to be sure I can remove all metals from the water. I plan to document my steps here in the hopes this helps someone else as well as encouraging anyone who’s had experience with this also to chime in with any tips as I go along.

First I plan to remove all the metal stains with an Ascorbic Acid treatment after a full clean and refresh of the DE filter, this has proven successful to me already a few times this year. I won’t be using the filter during the water change process but having a fresh filter for when the process is complete will be important to avoid any added metals that might be in the DE currently.

Next, I’ll cover the 11x24 pool with a 25x36 foot tarp (pool is around 5 feet deep from coping to pool floor all around) to be able to separate the fresh water from the old pool water being removed.

To be sure no metals are entering from my water source I have tested my well water and it shows low metals, but to be extra cautious I will also attach a Metaltrap filter which should be able to filter 1ppm of metals out should any come through. My water system at home also has a whole home cartridge filter and a water softening system, and my hose spigot is connected to this system. I understand some homes have outdoor water that does not get fed through the water filter and softening system, but this is not my case. Considering my water has metals in it the source must have been the well at some point but why the well water shows low metals now is anyone’s guess. Might have been cheap algaecide with copper the old owner/ pool maintenance used, I can’t really be sure. Either way, the metals were in the water before I owned the home so regardless of the source, step 1 is removing them.

My well pump and pressure system are fairly old, so in order to be sure I don’t cause any trouble to my system, I plan to fill the pool at a significantly reduced rate, so as to not over burden the system. The outdoor spigot runs a bit over 5 gallons per minute on full, but I plan to run the water at about 1 gallon per minute for my waking hours, and turn the hose off at night to let the well water refill underground just in case. The added bonus is that the MetalTrap filter should work better at slower rates also, although it does say it can handle 4-8 gallons per minute, but slower is better.

To remove the water under the tarp, I plan to use an inline water pump water. I’ll drain close to half of the pool and turn off the pump, cover the pool and the hose to the pump with the tarp, and begin refilling. Once full again, I’ll start the inline water pump again drain the rest of the water below the tarp while simultaneously filling the pool with fresh water above the tarp. I plan to lightly secure the tarp with some small stones to keep it from blowing around in the wind but to still allow the water on top to pull the tarp down to say on top of the water below.

It should be cool enough (about 60-70F high temps, lows in the 50s) that even though I expect this process to take a number of days that I don’t have issues with algae in the new water, but just to be sure I’ll throw my floater in there and some dichlor tablets in a light effort to begin to add CYA to the water too, for when the water change is complete.

It’s definitely autumn here now so I’ll be scooping leaves out twice a day during this process.

If anyone sees any holes in my plan, let me know! Any and all feedback is welcome. I’ve read so much on TFP this year and so much here has helped me formulate this plan to be sure I do this safely without breaking anything but I certainly could be missing something.
 

Msch99

Gold Supporter
Bronze Supporter
Jun 11, 2018
908
Verona, MO
Sounds like a well thought out plan to me! You may want to be in the 2 or 3 gal/min range though.
8k gallons/1gal min =133 hour exchange.
2 gal/min 67 hours
3 gal/min 44 hours
Good luck on your mission! :)
 
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revitup

Gold Supporter
Bronze Supporter
Nov 30, 2019
432
Pawleys Island, SC
Pool Size
8500
Surface
Fiberglass
Chlorine
Salt Water Generator
SWG Type
Hayward Aqua Rite (T-15)
Put a hose to the bottom of the pool under the tarp so you can pump water under the tarp when complete in case it is difficult to free from the bottom.
 
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JoyfulNoise

TFP Expert
Platinum Supporter
May 23, 2015
17,707
Tucson, AZ
Pool Size
16000
Surface
Plaster
Chlorine
Salt Water Generator
SWG Type
Pentair Intellichlor IC-40
Read this thread -


You need to be very careful when you get to the end. As you can see, @carlos31820 almost had a liner tear from the submersible pump sucking the tarp in. I would not try to get every last drop of pool water out, a few inches of old pool water will do you no harm. Be safe and keep family & pets away from the pool while doing this.
 
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mknauss

Mod Squad
TFP Expert
Bronze Supporter
May 3, 2014
37,059
Laughlin, NV
Pool Size
6000
Surface
Fiberglass
Chlorine
Salt Water Generator
SWG Type
Pentair Intellichlor IC-40
Please be aware of the risks of using the tarp. Especially to people or pets. You must be very careful there are NO children or pets near the pool during this process. The risk of drowning if one falls in to the pool during this is very high.

It is of little use to put trichlor (not dichlor) tablets in a floater during this. A bit of liquid chlorine if you like, but be careful near the edges of the pool.
 

Dtrav118

Member
Sep 16, 2020
23
Easton, CT
Put a hose to the bottom of the pool under the tarp so you can pump water under the tarp when complete in case it is difficult to free from the bottom.
Can’t I just fold the tarp edges into the water to break the seal? The water on both sides of the tarp should equalize the pressure on the tarp I would think? In any case, with an external in line pump I will still have a hose under the tarp which I can reverse the pump in order to put water under the tarp should it be necessary to do so. I guess we’ll see. If I have to rip the tarp too, I will. I’m sure with a tarp this big cut into 1/2s I will still have use for both large pieces eventually.
 

Dtrav118

Member
Sep 16, 2020
23
Easton, CT
Read this thread -


You need to be very careful when you get to the end. As you can see, @carlos31820 almost had a liner tear from the submersible pump sucking the tarp in. I would not try to get every last drop of pool water out, a few inches of old pool water will do you no harm. Be safe and keep family & pets away from the pool while doing this.
I read the entire thread previously which very much helped me form my plan, thanks for passing along! I’m working with a fiberglass pool so fortunately don’t need to worry about a liner. And yes we will keep pets and people away from the pool during this process as I know there is a major elevated drowning risk getting caught in the tarp. Thanks for the advice.
 

Dtrav118

Member
Sep 16, 2020
23
Easton, CT
Please be aware of the risks of using the tarp. Especially to people or pets. You must be very careful there are NO children or pets near the pool during this process. The risk of drowning if one falls in to the pool during this is very high.

It is of little use to put trichlor (not dichlor) tablets in a floater during this. A bit of liquid chlorine if you like, but be careful near the edges of the pool.
Thanks for the advice on the drowning, and good to know I’ll use some bleach instead of the floating tablets. The water from the hose will be 55F so hopefully won’t need to worry much about new algae during the process which is why I waited until autumn.
 

Dtrav118

Member
Sep 16, 2020
23
Easton, CT
Sounds like a well thought out plan to me! You may want to be in the 2 or 3 gal/min range though.
8k gallons/1gal min =133 hour exchange.
2 gal/min 67 hours
3 gal/min 44 hours
Good luck on your mission! :)
Thanks! The process should start tomorrow once I am able to round up all my supplies. I know it may take a long time, I also did the hours conversion too (I’m an accountant...seems to be lots of numbers people here, maybe I should start recruiting from this site) but I’d be much happier taking my time than somehow damaging the home water system by running the well dry. Especially since it’s cool here now and the water will be 55F coming from the hose, I don’t expect I’ll have too much trouble fighting algae with a little bit of chlorine over the course of then time it takes. And if I get some algae, so be it! I will finally be able to SLAM the pool and get ahead of it once the water change is completed vs what I was trying to do all summer with not shocking the pool so the metals don’t reappear on the walls...piece of cake! Hoping to send successful progress updates soon on this thread, wish me luck!
 

Dtrav118

Member
Sep 16, 2020
23
Easton, CT
2FB8FF3E-12A1-4DB6-A2FC-BAD7228E09D5.jpeg
Tough to see here but the ascorbic acid treatment did it’s thing, this is mid treatment. Then I backwashed and cleaned the filter, drained half the pool, got the tarp over the water, set up my hoses under the tarp, and began filling with the metal trap today at 1gpm to make sure no issues with my well.

I set up 2 hoses under the tarp, and set them up to siphon, rather than using a pump. I have a pump to use but I won’t need to use it except for turning it on once in a few days once the pool is full again, separated by the tarp between the old and the new water, so figured I’d save myself the noise, electricity, and the risk of not timing it correctly to stop the pump and prevent damaging the tarp and pump. I clamped off the siphon hoses with the siphon pressure going so I can just un clamp them when I’m ready to drain the remaining amount.
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Also I built some screen covers out of PVC and some mosquito netting to keep leaves and debris out of the pool. I need something for during this process but I also need something for the future since we have a lot of trees around our pool and no matter what I do or what season it is, I have found myself needing to skim daily, scoop daily, and vacuum the pool every 2-3 days, and daily for all in the late spring/early summer and even more than once a day for scooping necessary in the fall! The solar cover makes it worse since everything soaks on top of the cover and falls to the bottom once I remove it. This will allow light in to heat the solar cover but no debris. I may replace the screening with something a little more durable in the future but for now this was a cheap test for proof of concept.
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Planning to post more progress in a few days.
 

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Dtrav118

Member
Sep 16, 2020
23
Easton, CT
A few more photos as so far I haven’t screwed anything up. The tested water so far shows no metals, and the pool is about half way full. I was able to drain the remaining old water with metals from underneath the tarp with the siphon hoses overnight last night. I easily removed the tarp this morning by folding the corners of the tarp into the water and breaking the vacuum seal.

The water from my well is showing:
FC - 0
TC - 0
PH - 8.4
ALK - 140
CH - 60 (water softener seems to still be working even in this massive quantity
CYA - 0
COPPER - 0.0
IRON - 0.0

So, I added a bit of dry acid to bring the PH and ALK down to normal range (aiming for 7.6) for the 1/2 full pool, and some Dichlor additionally lower the PH but also to add a little Chlorine and CYA while the pool is still filling. I think I’ll be done filling in 2 more days, slow and steady at 1gpm so I don’t ruin the well pump, filters, etc for my home water system.

0B3772F4-8941-4203-BBF5-15FFCDA9A159.jpeg
8E6580F9-3AAB-4A71-9AEE-BF8465DA6E48.jpeg7A4CE380-30D8-4A20-9690-E037FC928B7A.jpeg
 

Dtrav118

Member
Sep 16, 2020
23
Easton, CT
Pools full and took almost 7 days at 1-1.5gpm, shutting the hose off overnight to prevent any issues with the well and to be sure I could monitor as we were going along. The only thing for me to be grateful for due to the COVID environment we’re in now is the flexibility to work from home which allowed me to closely monitor. Over the past 3 days I’ve brought up the FC level slightly just to be sure no contaminants, but with water temp between 55-60degrees I didn’t really expect any issues anyway. So far so good, no staining! Even with very high PH and alkalinity. The full pool read this morning at:

FC 0.5
TC 0.5
PH 7.9
ALK 133
CH 29
CYA 6
COPPER - 0.0!!!
IRON - 0.0!!!

I’m really happy with the progressI’ll add a bit more Calcium and CYA this weekend to get the levels a bit more normal and make sure my CSI level isn’t too low, and then close up for the year with the hopes and sweet dreams of a much easier year #2 in pool management. I plan to report back in the spring too!

Thanks go to everyone for your advice in getting me this far without breaking anything. Here’s a before and after picture in similar sunlight to see the difference between the copper/iron stained walls and water, and then the result after AA treatment and full drain using the tarp.



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