Green Hair Problem After Using Bioguard Smart Shock

[SnoopysGirl]

Thank you very much!

I am still very confused as to why it says that I have a 21,000 gallon pool in my signature. I have an in ground 18x38 pool 3ft shallow 8ft deep, roman shaped with bumped out step. When I use online pool calculators, they indicate a 28-29,000 gallon pool, and the company that takes care of our pool says it is 33,000 gallons. I usually average everything out and say 30,000, but I want to make sure that I have all of the values correct before I start adding chemicals. It just seems like it is a huge difference. Thanks, again!!

[PoolDoc]

I am still very confused as to why it says that I have a 21,000 gallon pool in my signature. I have an in ground 18x38 pool 3ft shallow 8ft deep, roman shaped with bumped out step.

Here's why:

the top 3' level of pool is LESS than a full 18 x 38 rectangle, assuming your measurements are greatest length and width measurements. In other words, the top part of your pool will fit into a rectangular box, 18 x 38 x 3. But your water depth is going to be LESS than the maximum pool depth, which is normally stated to overflow level, rather than actual water level. So the box is 18 x 38 x 2.8 cft or about 1850 cft OR 13,800 gallons.

Most vinyl pools have nearly flat shallow ends, and the break begins at the midway point. That in turn means that the bottom or deeper section of your pool will fit inside a rectangular box that is 18 x 38/2 x (7.8 - 2.8) or 18 x 19 x 5. That means the absolute maximum volume in the deeper section of your pool is 1710 cft or 12,800.

So, even if your pool was shaped as 2 stacked rectangular boxes, with right angles and no slopes, the upper box (18x38x2.8) resting on the lower box (18x19x5), your absolute maximum pool volume would be 26,600 gallons. If you add 500 gallons for the steps, you'd still only be 27,100 gallons.

BUT, the shape of almost all vinyl pool 'hoppers' -- deeper sections -- is highly sloped, with only a SMALL flat rectangular area at the full depth. Most hoppers are LESS than 1/2 the volume of a rectangular box with the same dimensions. In that case, your pool volume (if we use a hopper at 1/2 rather than something less would be 13,800 (top) + 500 (steps) + 12,800/2 (bottom) or 20,700 or ~21,000 gallons.

If you want an more accurate measure, if you can find the "DIG DRAWING" for your liner, it will usually have a very accurate CAD calculated volume for that pool & liner . . . at the OVERFLOW level of your pool. So, if the normal level is 6" below the OVERFLOW level, you need to take the CAD volume, and subtract 18x38x0.5x 7.48 gal/cft, or 2550 gallons from the CAD measurement.

Pool builders and pool stores almost ALWAYS overstate pool volumes!

Plus I can tell you -- having taught numerous Certified Pool Operator classes, a majority of pool builders can not calculate pool volumes accurately. Trying to get them through that part of the material was always a struggle.

[SnoopysGirl]

Ben, I am so very grateful for the amount of time you and the staff here have spent helping me with my pool. Thank you! I have read through all of the posts from page one, and I am going to do the following things:

1. Test FC, CC & pH daily with the Taylor K2006 kit.

2. Purchase HEDP and Culator to remove any copper and other metals from the pool.

3. Return the Inhibit Algicide and purchase Polyquat 60 Algicide, and use that to prevent an algae outbreak.

4. Purchase and use Borax to raise pH if/when needed (not sure on amount to use - can use guide)

5. When trichlor tablets are gone, begin to use liquid chlorine from hardware store at 10% strength. I am confident in the %, as the store goes through a lot of the bleach for a local company, and it is stored in air conditioning. Based on the Best Guess Chlorine chart, I will want my chlorine level at 8-15 ppm. Based on the calculations provided, 5.5 x 0.10 x 8.5 = 4.7 ppm of chlorine per gallon - adjusting the amount per pool needs. *Question* do I add chlorine to 8-15 ppm daily, or add chlorine to 15, then let it drop to 8 ppm, and do I have a good understanding of how I am to be chlorinating the pool?

6. This is the only part I don't understand: Bromide - I don't know what I need this for, and when I would use it.

I hope I have a good handle on all of the information provided in this thread and on the website. Thank you, also, for the pool volume explanation.

[SnoopysGirl]

In waiting for Ben to reply, I have taken a photo of the stain that is developing in my pool. I think it is probably iron, but I guess it could also be copper. I did the ascorbic acid test today. Here is my photo:



Will the HEDP lift this stain, or does that just take metals already in the water OUT of the water? I am thinking that I will need to treat the stain. Stain treating products have specific recommendations for pool chemistry, and unless there is some miracle product out there, I won't be reducing the CYA by the amount needed. Any advice would be great - thank you!!

[PoolDoc]

The last test indicates that the CYA is 270.

This is the only part I don't understand: Bromide - I don't know what I need this for, and when I would use it.

Assuming the CYA=270 is still correct, sodium bromide will allow you to kill algae without having to raise your chlorine level to 100 ppm or something like that. We're going to TRY to avoid having algae. But, you don't want to bet the farm on succeeding, so you need a backup plan in case you fail. Sodium bromide can be hard to buy locally, so I'm recommending that you purchase it, keep it on hand, but hopefully, never actually use it!

I did the ascorbic acid test today. . . . . Will the HEDP lift this stain, or does that just take metals already in the water OUT of the water?

HEDP might lift the stain, but probably won't. It also won't take the metals OUT of the water; it does EXACTLY the OPPOSITE! It keeps the metals IN the water. The clean up sequence is:

1. Ascorbic acid lifts the stain OFF the steps, and puts the metals IN the water.
2. HEDP *keeps* the metals in the water, once you re-chlorinate (which destroys the ascorbic acid)
3. The CuLator unit + constant filtration REMOVES the metals FROM the water.

All three steps are essential.

[SnoopysGirl]

I visited the pool store today. Unfortunately, they didn't have the HEDP so I will have to order that. They did say that it is fine to use the liquid chlorine, and they did also show my level of CYA at between 270-300, so they didn't try to sell me more stabilized chlorine, though they did recently sell me a BioGuard shock product and told me to use that to chlorinate the pool. Unfortunately, that is also stabilized chlorine, so it will also increase my CYA level.

Question: when reading online, an article mentioned that salt is a byproduct of using liquid bleach in a pool. Is this correct, and if so, is my water going to taste salty? How do I prevent that??

[aylad]

Salt is a byproduct of using bleach in the pool, but the amount is negligible--you won't be able to tell. I've been using bleach in my pool for 11 years now, and the water still doesn't taste salty.

Janet