brown, green pool

[vwb1975]

i have an AG with a sand filter. the gallon size is 14000. i have been using the bleach calc, and have been testing daily. but i have brownish green water. i have used metal out. didn't seem to help. here are my test results as of this morning.
TA=200
PH=8.0
CL=5.0
CYA= 10
i put in some algecide and now i have brown foam on the top of the water. i drained it about a quarter of the way and refilled it. i have well water. i took a sample to the pool store and the iron and copper were normal. i have been vacuming to waste and brushing the sides. it has been five days and there is no change. any info as to what might be the problem?

[vwb1975]

today after adding 3 gallons of bleach, and brought the ph down to 6.8, the foam started to subside and i noticed white clumps on top. but, it looks like dirty water is comming in through the return jet. i have backwashed it earlier. i can post a pic if that will help with the suggestions. Tomorrow i plan on taking a look at the sand in the filter. i noticed that when i was backwashing, there was alot of sand in the looking glass. is that normal?

[aylad]

There is no "normal" range for iron and copper. Do you mean they are zero? Or do you have one or both in your water? If so, I strongly encourage you to go to the "metals" forum and read through everything you can there, especially any post made by mbar (Marie) who is one of the resident experts on metals in the water around this forum. I see that you have high pH and Cl (for a CYA of 10), and I believe those are two things that adversely affect your attempts to use the metal sequestrant.

Janet

[CarlD]

You may well have a lot of iron in your water--have a pool store test a sample for iron.

Edit:

Please don't double post. It will get seen. I've deleted the thread you started with the same post as above.

[vwb1975]

i took the sample to the pool store and the result was iron and copper are ok. they didn't give me a number on it though. Last night i took the top off of the filter and the sand was brown and stinky. there was also alot of green clumps on the top layer of sand. so hopefully this week, i can get some new sand and see how it will filter. i throughly cleaned the inside of the filter.

[aylad]

As I said, there is no "okay" for iron and copper, except for zero. How you chemically treat your pool is very different if you have metal present than if you don't.

Janet

[vwb1975]

okay. do you know of a test for metal that will give me numbers? the test kit i have only tests for cl, ph, ta, and acid demand.

[PoolDoc]

With very few exceptions, there will be no copper in your water, unless you added it, or unless you corroded it off of a pool heater. So, to check for copper, check your chemical product labels. (NOTE: you are actually going to have to READ the fine print on the chemical ingredients, to check this.) If you haven't added anything that has copper in it, and don't have a heater, you probably don't have copper.

Iron is common is well water. If you have it, you probably already know that. If you have a softener, it will also remove the iron from the water . . . and you should fill your pool with that. Removing iron from an AG pool with a sand filter is not the easiest thing in the world. The sand filters are almost always 'over driven' (ie, the pump's way too big for the filter) and the precipitated (orange rust dust) is blown right on through the filter. Of course, if you do refill with softened water, you'll most likely need to be prepared to regenerate your softener several times.

But, green is not a common color from metals. If your filter is slimey and stinky, and has green slimey clumps, almost certainly, your problem is simply good old algae due to a lack of pool chemical maintenance. Replacing your sand won't necessarily help, unless you've blown a lot of it out during backwashing (also common on AG pools with oversized pumps and undersized sand filters -- and almost all of them have this combo, if they have a sand filter!).

Your reported TA is high enough to encourage algae, so it would also be useful if you take advantage of that low pH, and aerate your pool which will both raise the pH and remove some of the carbon dioxide from the water (ie, carbonate alkalinity). The full story on this is in the Alkalinity section, posted as a 'sticky'.

It's also worth noting that with initial chemical conditions including an alkalinity greater than 200 and a pH greater than 8.0 and a chlorine level greater than 5 . . . the chance that there are any dissolved metals left in the water are almost nil. High pH tends to cause metals to drop out (precipitate or stain), as does high alkalinity, as does high chlorine. Put all three together, as you report, and the metals will no longer be IN your water. They may be staining something somewhere, or on your filter, or on the pool bottom, but they are probably not IN the water.

So, it really sounds like your most likely problem is algae with poor filter function. Making sure you have enough sand is a good step. Making sure that your pump is not overdriving the filter is a critical one! Here's a guide, based on sand filter diameter:

14" diameter => 1.1 sft surface => 16 gpm max flow => 13 gpm optimal flow
19" diameter => 2.0 sft surface => 30 gpm max flow => 25 gpm optimal flow
20" diameter => 2.2 sft surface => 33 gpm max flow => 27 gpm optimal flow
24" diameter => 3.1 sft surface => 47 gpm max flow => 39 gpm optimal flow
30" diameter => 4.9 sft surface => 74 gpm max flow => 61 gpm optimal flow

Please note that these flow rates are as little as 1/2 of the listed rates, on AG pool filters. But, if you go with those bogus rates, you just end up pushing dirt through the filter, instead of trapping it. The solution is to either get a bigger filter or a smaller pump, or to throttle back the pump to make it 'smaller'.

Ben