How to differentiate between algae and iron/metal problems?

What is floc, clarifier, stabilizer, cyanuric acid,
algaecide, brightener, dichlor, sodium hypo,
sodium bisulfate, ....??

How to differentiate between algae and iron/metal problems?

Postby BulbDroid » Wed 30 Apr, 2008 18:22

I've done regular maintenance to my pool and periodically check pH/Chlorine levels and experienced algae, cloudy water, oily/film floating substances, bugs, larvae, etc.

Last week i realize that my filter was clogged and decided to add muriatic acid directly in the water suction to see if this was due to calcium buildup.

After half of the bottle it seemed to worked and the water jets in my pool began to spread a white cloud to the water.

After that, the water seemed ok to me, just tested for pH levels and then indicated a very acid water of course, i don't mind it and let the pump run in filter overnight just for the sake of completely unclog my system.

The next day my water turned absolutely green, but the water was transparent, no blurry/cloudy water at all, just like if somebody added food colouring to it.

Shocked the water just in case, with no results, tested the water and still very low pH (due to muriatic acid), then i decided to call my pool store.

They advice me to add Soda Ash to balance the pH and i did so, the levels turned to be ok but water still green with some kind of a orange slime deposits in the floor and 5 days after now the water became cloudy and with an olive green color.

I'm suspecting now of iron/metal problems in the water.

Which kind of generic chemical (no brands) should i ask for in my country to get rid of metals?

Thanks in advance.

chem geek
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Postby chem geek » Wed 30 Apr, 2008 18:38

You should never ever add acid directly to the skimmer or suction line. Even with the suction flow, it is still VERY acidic, only changing in pH from -1 to around 1 (assuming 100:1 dilution) which is still extremely acidic. I suspect that you corroded copper that may be in a heat exchanger in your gas heater or heat pump. You may also have damaged your pump seals and possibly your filter, depending on type.

If you had a problem with your filter, the solution would be to clean it -- backwash if sand, clean if cartridge, either clean or backwash if DE depending on type of DE filter (follow the instructions with the filter). You never, ever add concentrated acid to it.

You can buy chelating or sequestering agents that will try and keep metal ions in solution and prevent them from precipitating out. If you find that the green intensifies when the ph goes up, say after adding a hypochlorite source of chlorine, and if it is a clear green instead of cloudy, then it is most likely copper.

You need to have your system thoroughly checked out as there may be serious damage to it -- the heater, pump, and filter.

As for regular algae, this is most likely due to your Free Chlorine (FC) level being too low relative to the Cyanuric Acid (CYA) level. You may be using stabilized chlorine (Trichlor or Dichlor) and built up a high CYA level which makes the chlorine less effective. If you don't keep the FC/CYA ratio constant at a minimum FC of 7.5% of the CYA level, then algae can develop unless you use a supplemental algaecide on a weekly basis such as PolyQuat 60 or a phosphate remover.

It is unlikely that you had Calcium buildup in the filter. Usually, calcium will cloud the water and produce scale on plaster and tile surfaces and especially in a heater (higher temps cause more scaling). You can calculate the saturation index for your water chemistry using The Pool Calculator, but unless it is strongly positive, you probably did not have scale.


Postby BulbDroid » Wed 30 Apr, 2008 19:03

Thank you very much for the fast answer.

Btw, i hope there is no damage to the pump and/or pipes since everything is made of PVC and is running ok right now, no need a heater at all because i live in a tropical zone.

But i suspect i just began to corrode some kind of copper/bronze ornaments in the pool, and that was in purpose because for a long time they began to build some kind of calcium white dots, and nothing seemed to work to get rid of those, then with the over-acidic water those dots began to desappear.

The only problem seems to be the ugly water color.

I'll try for metal sequestering chemicals and promise not to put direct acid to the suction again :lol: .

Thank you.

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