green water - I don't think anymore algae

My water is green, but clear. We had a lot of acid rain here over the past few weeks, while I've been trying to clear it. The water is clear, and holding CL (shock levels) for several days, so I do not think it is algae hanging out waiting to be filtered.

I was vacuuming to waste a lot, but even with the rain, I've added 10 inches to a 20x40 vinyl pool (30K gal) from a well between startup and vacc'ing to waste. We do not filter our cold water - just the hot - so it came right from the ground. Sometimes even the bath water has a green tint to it, so I know there is either copper or iron in the water. The liner is stained too.

So, how do I really tell that it is a mineral v. algae? I had quite an algae issue at startup, so it is possible it is still in the water, but I don't see the dead stuff on the bottom anymore. I will take a sample to the store tomorrow, but does my steady CL levels indicate the algae is done? I know I can't do a stain removal if I need to shock within a few weeks. Is the method of putting ph+ on something and rubbing the stain a good indicator of a mineral?

Numbers are:
TC 11
CC 0
FC 11
alk 110
ph 7.2 (finally!)
CYA - between 20-40
30K gallon vinyl

Just need a direction. I have some stain remover but don't want to waste for at least a few weeks to be sure the CL can be left at lower levels without new algae. Plus that water is 60, so we aren't going to be swimming any time in the next few weeks.

We are having a big party on Father's Day weekend, and I really would like the water to look more normal that the clear green water I have now.

Clear green water is usually a possible indication of copper. Iron will create a yellow to brown color in the water and if you have a blue liner it can look green. Get your water tested for metals. That is really the only way to tell. If you test positive for copper or iron then you would need to add a sequestering agent.

OK, went to pool store today and they said no iron or copper in the water. But the white steps and wide stripes in the shallow end are stained. Would that mean that copper is out of the water but instead of filtered out, it stained? Does that make any sense?

I think I do still a bit of algae, so the water color is probably from that. I shocked to 15 on Tuesday night, and it was down to 2 today (48 hrs later). It was holding CL better than that last year at the same CYA level of 35.

If you think the stains could be from iron/copper that is out of the water, I will do Ben's suggested process of lower ph (I am at 7.2, so that should be OK), lower CL (normal - 2.5 for me), polyquat, add the metal remover product, filter for a week, bump up ph, slowly add CL to 10. This worked for me last year, but I had an algae bloom and shocked - which put the mineral back to staining again - since it was before all the metal got filtered out. Does that sound like the correct process if indeed it is mineral stains?

- betty

It sounds like you do have algae, if you are losing chlorine that fast, something is probably eating it up. I would get rid of the algae first by getting your chlorine up to shock level and keep it there.

Stabilizer . . . . . . Min. FC . . . . Max FC . . . 'Shock' FC
=> 0 ppm . . . . . . . 1 ppm . . . . . 3 ppm . . . . 10 ppm
=> 10 - 20 ppm . . . . 2 ppm . . . . . 5 ppm . . . . 12 ppm
=> 30 - 50 ppm . . . . 3 ppm . . . . . 6 ppm . . . . 15 ppm
=> 60 - 90 ppm . . . . 5 ppm . . . . . 10 ppm . . .. 20 ppm
=> 100 - 200 ppm . . . 8 ppm . . . . . 15 ppm . . .. 25 ppm

With a cya between 30 & 40, you need to get your chlorine up to 15ppm, and keep it there until you can hold it overnight.

You can test if the stain is mineral by putting some crushed vitamin C in a sock and rubbing it on the stain. If the stain lightens or goes away it is mineral, if not chlorine should take care of it. You can also use some ph down in a sock the same way as the vitamin C.

I agree with MBar. If the FC is not holding something is eating it up. Metals don't do that. Take care of the chlorine demand first and then worry about treating the stains.

OK - I am dealing with algae filtering first, then the stains. The stains really bug me though :) The water is much clearer today after another day of 15 CL, so I'll wait a few more days before moving on to the stain. Thanks.