brown algae or sand on the bottom of my above ground

[atlantafalcon]

I have the same problem with what we thought at first was sand at the bottom of the pool. We have an Intex 14' above ground with an Intex 8110 saltwater system. The stuff forms along slight ridges throughout the bottom and will eventually turn black and become more difficult to scrub-off if the bottom is left undisturbed. The pool store told us to clean the cells in the SW generator, since it was just deposits (calcium?). Cleaned them this weekend and the stuff is back.

After reading this thread I went outside and scrubbed a spot with a hand brush. I saw a tiny piece of green plant material floating, as I had after scrubbing in the past, and grabbed it to put in a container to carry to the pool store. This is algae of some sort. Whether it's brown, mustard, or black I don't know, but the stuff is annoying.

[kaptn35]

I have been battling this as well. I vacuumed one time via filter and the next day even after shocking it was coming back. Last night I vacuumed to waste.....Pool looked perfectly clear after doing this. I then turned on the water to start refilling and added Baking Soda to increase the Ph and Alkalinity (not a good move!). I then poured in Jacks Yellow Stuff Algacide to attack the Mustard Algae. Followed the directions percisely and after pouring that in I started to shock the pool with Dichlor Granules. WHOAAAA....pool turned a lime green like a fog bank rolling thru the water.

I could have copper elements in the pool? Not sure if Jacks Yellow stuff is a Copper Algacide because it says nothing on the bottle. Would the Baking Soda cause this reaction? I plan on going home tonight and shocking the pool since my free Chlorine is showing only 0.7. If I get an reaction then most likely a metal agent in the pool. If not then it was either of those chemicals that caused it.

My stats as of this morning:

FC 0.7
TC 1.6
CC 0.9
TA 139
PH 7.2
CA 30
Copper 0 (quite surprised at this)
Iron 0

[Richard42]

What are the steps to keep this brown algae from even showing-up?

[chem geek]

First you need to completely eliminate the yellow/mustard algae as it is harder to get rid of. One must get behind light niches and under removable ladders and shock the pool with a Free Chlorine (FC) level that is 60% of the Cyanuric Acid (CYA) level. Add poles and other items that go into the pool so they get shocked as well. Wash swimsuits.

Then after the algae is killed, you maintain an appropriate FC for the CYA level. Read the Pool School for more info including how to shock the pool, defeating algae, and the chlorine / CYA chart.

Also note the following chemical rules of fact that are independent of concentration of product or of pool size:

For every 10 ppm Free Chlorine (FC) added by Trichlor, it also increases Cyanuric Acid (CYA) by 6 ppm.
For every 10 ppm FC added by Dichlor, it also increases CYA by 9 ppm.
For every 10 ppm FC added by Cal-Hypo, it also increases Calcium Hardness (CH) by at least 7 ppm.

So even with a low 1 ppm FC per day chlorine usage, continued use of Trichlor pucks/tabs will increase the CYA level by over 100 ppm in 6 months if there is no water dilution. Since the active chlorine (hypochlorous acid) concentration is proportional to the FC/CYA ratio, higher CYA levels mean lower active chlorine that eventually gets to the point where algae can grow faster than chlorine can kill it. So getting algae is not a surprise when using such products.

[rpuryear]

The sand is so fine that the filter is having a hard time trapping it , so vacuum it to waste!

[neebassoci]

I have been having the same problem with a brown, very fine, sediment-like substance that has been appearing in the bottom of my above ground Intex pool nearly every day. My filter recently quit working. A neighbor, who was pitching his Intex pool into the trash, gave me his filter, which still worked quite well. I thought I did a thorough job of cleaning his pump and then hooked it up to my pool. Shortly thereafter, the sediment began to appear. Obviously I had introduced an alien species into my pool from his filter. After repeated efforts to vacuum the sediment through the filter, I realized that the sediment was passing through the filter without being captured. I caught a glimpse, just out of the corner of my eye, of what appeared to be a pale brownish plume shooting from the pump outlet and back into the pool as I was trying to vaccum the stuff out. I finally discovered that the cure was to apply basic physics to the problem. I used a large dose of algicide afterwhich I bought about 3 feet of PVC pipe and 15 feet of flexible tubing and hooked it all together. I submerged the whole assembly in the pool until it was full of water. I left PVC laying on the bottom of pool while I plugged the flexible end with my hand. I then lifted the flexible end out of the pool, removed my hand and, viola, I had a very effect siphon with which to vacuume out the sediment. The siphon sucked the sediment out of the pool and directly to the ground, ensuring that it would not be reintroduced to the pool water. I have done this for a couple of days now and most of the sediment seems to be gone. In couple of weeks I will drain the pool for the winter and will thoroughly sanitize the filter so that I don't have this problem next summer.