Has anyone succeeded at shocking a green pool without using the pump to circulate?

Don't know about the CYA.
On the chlorine, I planned to use the 1 lb packs from Lowes. I think it said the active ingredient was 53% but can't remember exactly what it was. Would that make a difference?

Any form of chlorine can kill algae. I don't know what the 1 lb. packs from Lowe's are, but I suspect they are dichlor. All pools need some CYA but when it gets too high, then you need to keep your chlorine levels higher and higher in order to keep algae at bay. Some forms of chlorine are stabilized which means they have CYA (cyanuric acid) in them. Trichlor tabs (like what you put in a chlorine feeder) and dichlor powder are both stabilized.

Many people are not aware of the connection between CYA and needed chlorine levels. They use stabilized forms of chlorine for long periods of time and then don't keep their chlorine levels where they need them and then end up with algae. We see this all the time -- people who have algae and can't figure out why.

The reason I asked if you knew your CYA level is because if you knew that your CYA level was already high, I was going to recommend against using dichlor shock and instead using either bleach or pool store liquid chlorine (which is the same ingredient as bleach at a higher level and usually a MUCH higher price!)

You can read more about the CYA and chlorine connection in the Best Guess Chlorine Chart in my signature below.

EDIT to add that some pools (not all) lose all their CYA over the winter anyways so it may not matter.

Don't know about the CYA.

I planned to use some Shock bought at Lowes. Says 53% Sodium Dichloro triaz something.

What ingredient should I be looking for?

Dichlor is fine - given cold water, you'll need to pre-dissolve it, to keep it from sitting on the bottom.

The problem is the 53% . . . if it's 53% available chlorine, you're OK. If it's 53% dichlor + 47% other stuff, not so good. Some of the other stuff they blend with, is not what you want to put in your pool. If you can tell us brand and EXACT product name, we can probably find out.

It's Aqua Chem 'Shock Plus'

The box says 58% chlorine.

Somewhere I think I read that it has some flock in in and maybe a few other things...not sure where I saw that, as the mfg site is very sketchy, as is Lowes.

There is a some info on the box.

It's probably OK to use now, but you won't want to use it, once your pool is open. It's got alum in it -- floc -- and will have some tendency to create a fluffy layer of settled debris.

Hi Ben,

I wonder if I can hijack my own posting? Here goes...

As mentioned earlier, I'm trying to clear the water so I can refill it and dye test 5-6 vertical hairline cracks located around the sidewalls, and generally running 12" to 30" below the normal surface of the water.

It's a concrete pool with a quartz plaster finish. The cracks are so fine that you can NOT even catch your fingernail on them. So the options:
1. Run some clear silicone over them, for now
2. Cut out a narrow slit, the width of a small diamond blade, and fill it with plaster
3. Epoxy the surface ,,,or some combination of the above

Right now, I'm wanting to trouble shoot the leaking and don;t mind doing something temporary until I can verify if these cracks are the source of the leak. I'd rather not just fill it without at least trying something on the cracks initially.

Any ideas/ suggestions are much welcome! :)

Back on the original topic!

Shocked the pool today with 4 lb of Lowes shock. The faint green is now more blueish though cloudy.

I've got the pump running and filtering. I'm a novice at this so I hope someone can kindly help with a few basic questions:

1. Our temp here is about 60 and the water temp is likely more like 50. How long does shock usually last and when to I begin regular chlorinating.

2. This is a vacation house and I live 3 hrs away. Is it ok to let a pump run for a week without backwashing (since that's when I will return). I have a large sand filter and it usually runs at about 18psi. If that's too long I'll just have to turn it off until I return next weekend.

3. I'v never backwashed before. About how long do you run it in backwash, and how long rinse? Am I right that when you back wash you open the valve on the pvc waste pipe at the same time? It's a standard multi-port valve on the filter, and I can't recall if it has a separate setting for backwash and a separate setting for waste.

Many thanks. sorry I know so little, though I'll know a lot more after the first time!

I thought I got a not about now being officially registered, though my posts seem to still require approval. Is there a step I need to take to fix this? tks

I can tell you a little about backwashing. A standard sand filter with a multiport valve will have a "backwash" setting. Select it. Attach a length of hose to the waste pipe and run it away from the pool. Make sure the pool is full as the backwash and rinse cycle can drain a lot of water out. During the backwash process water is forced upward inside the filter, stirring up the sand. Have a white plastic pitcher ready.

Turn on the pump. Dirty water will shoot out the waste hose. Watch it for 20 or so seconds, then catch a little in the white pitcher. If it still is cloudy or has bits of debris in it, let it run a little longer. When the waste water is clean, stop the pump.

Set the valve to "rinse" this is very important, don't skip this step. During the rinse cycle water enters the filter from the top and packs the sand down again. Turn the pump on again and rinse for 30 seconds. I normally do the backwash/rinse cycle twice and I always make sure the water level in my pool is higher than 1/2 way up the skimmer.

Turn the pump off, set valve to "filter", disconnect waste hose. You may get a small amount of sand blowing back into the pool after a backwash. If that happens you either didn't rinse long enough or you may have a leaky spider gasket.

Good job on getting the pump and filter up and running!

There's no way to tell how long "shock" lasts. Depends on how much algae is in the pool and what the final FC and CC levels are. You're done adding high levels of chlorine when the CC stays at under 1 ppm. Clearing up a green pool is a process that can take several days. My preferred chlorine source is bleach or liquid chlorine because with those products all I add is chlorine and I can calculate fairly accurately how much I need to achieve and maintain the desired shock level of FC.

If your pump is solid and reliable then yes, you can let it run during your absence but don't be surprised if the pool is green-ish again upon your return. It's critical to maintain chlorine at shock levels when clearing a pool, it just is not a one time application.