Do I Need To A Partial Drain/refill?

[tabbikat86]

First of all I have an easy set intex pool that is 18 x 4 ft, it holds 5500 gallons of water, I am using a 2000 gph filter pump that uses the B filters. I was on the aqua chem system that uses dichlor 1 in tabs (the whole system included balance products, sanitize, shock, and algaecide. I've been reading a lot of posts on here and was told that the dichlor then bleach method would probably work...and I was using test strips (i know not accurate) and it had my cya levels as around 40, but I took it to the pool store and I trust their results over the test strips and my cya level is at 80. From all my reading that is not good, although the pool store said it was normal... I'm ready to switch to bleach...but it seems like I will have to use a lot of chlorine. I was using this link http://www.troublefreepool.com/pool-school/chlorine_cya_chart_shock to determine how much chlorine and I believe I got that link from Nitro's approach to water maintenance...although it was talking about in hot tubs, I figured it was roughly the same. So my question is do I need to do a partial drain/refill? I really don't want to because I'm only keeping the pool up for maybe a month-month a half. I go back to school in August and it takes first priority...I won't have time to keep it up while I'm in school. And how much bleach should I use? The clorox company gave me this: use 1/8 a cup of unscented chlorox per 100 gallons of water. I figured that probably would bring you to 2 and if I need to shock it to 31, I would need to use about 15 times that. Which at 1/8 a cup per 100 gallons is roughly 7 cups in my for my pool...so to shock it I would need 105 cups? Does that sound right, or am I wrong? Please help, and thanks:)!

[tabbikat86]

I forgot to post my levels...duh, well anyways here they are:

CYA: 81

Tot Chlorine: 0

Free Chlorine: 0

pH: 7.6

Tot. Alk: 176 (high right?)

Calcium Hardness: 69 (but I have a vinyl pool so I don't need to worry right, b/c the levels are low and not high?)

TDS: 450

Those darn test strips...i bet my alkalinity was perfect the other day when the strips said it was low and I added a 0.5 lbs of alk increaser...well thanks!

[tabbikat86]

And one more thing if I do need to do a partial drain/refill, how much should I let out to get my cya levels where I need them. I was thinking with a cya level of 81, maybe I would need to drain half of it and refill it to get a cya reading of around 40.

[waterbear]

While it is true that you need to maintain higher FC levels with higher CYA levels your will not necessarily use more chlorine to achieve this. You will still lose about 1-2 ppm per day and since the CYA holds the higher chloirne "in reserve" you might not be adding chlorine as often. In fact, many pool services that visit weekly and use either gas chlorination or liquid chlorine use this to their advantage. They raise the CYA to around 100 ppm then chlorinate to shock levels. When they return a week later there is still enough chlorine in the water to prevent problem.

Get rid of the strips, they are useless for balancing your water, particularly if you are considering running higher CYA and FC. Get yourself a Taylor K-2006. You won't regret one penny spent on that test kit AND the FAS-DPD test is the only one that is really workable for maintaining higher FC/CYA. With every other chlorine test you will have to dilute your pool water samples with distilled water, which is time consuming and lowers your accuracy.

Drain and refill is certainly the preferred option but it is not your only one. 5.5k gallons is not a trivial amount of water to drain (my inground pool is only 6.5K!) but it is certainly easier than if your pool was 15-20k gallons!

[tabbikat86]

While it is true that you need to maintain higher FC levels with higher CYA levels your will not necessarily use more chlorine to achieve this. You will still lose about 1-2 ppm per day and since the CYA holds the higher chloirne "in reserve" you might not be adding chlorine as often. In fact, many pool services that visit weekly and use either gas chlorination or liquid chlorine use this to their advantage. They raise the CYA to around 100 ppm then chlorinate to shock levels. When they return a week later there is still enough chlorine in the water to prevent problem.

Get rid of the strips, they are useless for balancing your water, particularly if you are considering running higher CYA and FC. Get yourself a Taylor K-2006. You won't regret one penny spent on that test kit AND the FAS-DPD test is the only one that is really workable for maintaining higher FC/CYA. With every other chlorine test you will have to dilute your pool water samples with distilled water, which is time consuming and lowers your accuracy.

Drain and refill is certainly the preferred option but it is not your only one. 5.5k gallons is not a trivial amount of water to drain (my inground pool is only 6.5K!) but it is certainly easier than if your pool was 15-20k gallons!

so would I need to use more chlorine? 105 cups to get to 31? thanks for the info!

[waterbear]

so would I need to use more chlorine? 105 cups to get to 31? thanks for the info!

Where did the "105 cups to get to 31" come from?

IF you are referring to chem geeks chart for shock level at 80 ppm, in actual practice shock levels above 20 ppm are often quite sufficient. Your normal maintenance level of FC would be in the 6-10 ppm range. I would shoot for about 7-8 ppm. 1/2 gal of 6% ultra bleach will raise your pool about 6 ppm and you will not be waiting until the FC is at 0 ppm to add it so you will not need that much at one time. You will be chlorinating nightly or every other night most likely so you will not be adding that much chlorine at one time. Perhaps a quart or less.

If and when you need to shock you will need about 2 gallons or so of bleach IF your FC is starting at 0 ppm. If you just have a bit of CC to get rid of less will most likely suffice, perhaps a gallon or so.

If you use more concentrated pool store chlorine that is typically 12.5% then your amounts will be about half.

NOT a lot of chlorine at all.

Not sure where the 105 cups of chlorine came from. That would be 6.5 gallons of chlorine! assuming you are referring to 6% bleach that would raise the chlorine in your pool about 75 ppm, more than twice what you need and probably three times more in actual practice!

[tabbikat86]

so would I need to use more chlorine? 105 cups to get to 31? thanks for the info!

Where did the "105 cups to get to 31" come from?

IF you are referring to chem geeks chart for shock level at 80 ppm, in actual practice shock levels above 20 ppm are often quite sufficient. Your normal maintenance level of FC would be in the 6-10 ppm range. I would shoot for about 7-8 ppm. 1/2 gal of 6% ultra bleach will raise your pool about 6 ppm and you will not be waiting until the FC is at 0 ppm to add it so you will not need that much at one time. You will be chlorinating nightly or every other night most likely so you will not be adding that much chlorine at one time. Perhaps a quart or less.

If and when you need to shock you will need about 2 gallons or so of bleach IF your FC is starting at 0 ppm. If you just have a bit of CC to get rid of less will most likely suffice, perhaps a gallon or so.

If you use more concentrated pool store chlorine that is typically 12.5% then your amounts will be about half.

NOT a lot of chlorine at all.

Not sure where the 105 cups of chlorine came from. That would be 6.5 gallons of chlorine! assuming you are referring to 6% bleach that would raise the chlorine in your pool about 75 ppm, more than twice what you need and probably three times more in actual practice!

6.5 gallons and a 105 cups are virtually the same. 105 US cups = 6.5625 US gallons. I came up with that method by using what clorox the company told me. 1/8 a cup per 100 gallons. which would be 6.875 cups, or for my calculations, 7. That would bring it up to 2 (i thought...). So I figured to get to 31, I would have to use roughly 15 times that amount, and 15 x 7 cups is 105 cups, or 6.5625 gallons. But now I see that is wrong...so thank you!