Please explain this passage in the holy recommended pool chemicals page...

[TFP_Addict]

"Bleach should be added to the pool by pouring slowly in front of a return jet with the pump running. You should pour slowly enough that pouring an entire jug takes more than one minute, preferably two minutes. Leave the pump running for at least 30 minutes after adding bleach."

Why? What does it matter if you dump in the liquid or do it slowly?

 

[aeh0603]

Bleach is heavier than water, so if you dump it in too fast it will sink to the bottom and could damage your pool surface. If this happens, it also takes longer to properly mix into the pool water. Pouring slowly over a return jet prevents this. Another solution would be to thoroughly brush the area after pouring in the chemical to ensure it is mixed into the water and not just sitting on the bottom of the pool, but best practice is still to pour slowly into the return jet.

 

[Casey]

Because in the Holy Grail of Life they say blood is thicker than water... well so is bleach.

 

[TFP_Addict]

could damage your pool surface

Any examples of this unholy act! I wanna see!

Because i've dumped my holy water (chlorine) this way forever and never noticed any damage.

 

[RDspaguy]

It all depends on the overall circulation in your pool, but it can discolor and deteriorate liners and stain plaster. I always walk around the pool pouring slowly as I go and avoiding splashing by hunching over like quasimodo. But pouring in front of a return will spread it around and mix it in pretty well too. Don't splash on the coping or deck, or you may very well see an example.

 

[mariane]

I have bleached my vinyl liner in several spots because of concentrated bleach sitting in one area without mixing. 1st time was several years ago when we had 60 degree temp in March and the pool store told me to dump chlorine in the pool. Never mentioned the need to mix it up and the pump was not running.

 

[TFP_Addict]

Vinyl... Ok but plaster? Any evidence of this?

 

[RDspaguy]

I have seen it many times. High chlorine levels and high ph (which liquid chlorine has) bring dissolved metals out of solution causing staining. It is not really a one shot deal, but occurs over time. Ascorbic acid is tough to use around the main drain, so it often results in an acid wash.
But again, it all depends on circulation. But if you winterize your pool first and then dump a truckload of liquid in the deep end, you'll see what I mean come spring.
Sorry, but I don't have pics. It was just another tuesday for me.

 

[Rattus Suffocatus]

Yeah.. Luckily I do it when the pump is on high and in the deep end and have no issues whatsoever. But I add less than a third of a gallon a day and I am about to switch to a SWCG and add none. It depends on your pool... Mixing chemicals up good in a pool is always desirable.

 

[RDspaguy]

Mixing is necessary! The risk with your method is not to the plaster but to the pump, filter, and especially heater from pulling higher than normal concentrations through the equipment. But with as little as you use, I suspect you are ok there.

 

[Rattus Suffocatus]

I do not have a heater. So that is a consideration. If I were to ruin something by the way I do it (I do spread it out for feet in thd deep end) I would have by now.

 

[RDspaguy]

Yep. It would only be an issue if you were adding large amounts all at once, and then it would take many years to see any damage. But it can be the difference between 10 years or 15 in a heat exchanger.

 

[Rattus Suffocatus]

In my case it shouldn't matter because a SWCG will be online in a couple of weeks anyway. I was adding it fairly far away from the skimmer and main drain anyway. I mentioned that because it does depend on your pools configuration. I doubt if a high concentration of Cl ever made it to the pump. I imagine the plumbing and returns will see a lot more with the SWCG.

 

[RDspaguy]

Yes, but they are not likely to see the same damage that metal or de grids would.