Algae, but chem levels good?

Goliath · Oct 20, 2013

Haven't posted in a while because I "though" I had everything under control.

Just went out after a few weeks (on vacation) and green algae is growing at water line only on non-sunny side.

Levels as follows:

FC = 7.6, CC = 0
CYA = 45
TA = 70
PH = 7.5
CA = 390

Any idea why it's growing? FC seems way too high for swimming AND algae.

Tx,
D!

duraleigh · Oct 20, 2013

Likely due to poor circulation. Regardless, visible algae is a trigger to SLAM your pool and get rid of it.

Goliath · Oct 21, 2013

Thanks for the reply. I'm not sure that it's poor circulation as I have the pump running 8hrs/day. There are 3 returns at 45 deg angles that make the water rotate in an anti-clockwise direction pretty well.

It did rain last week, and I have not checked the levels since. Could it have grown that fast?

Richard320 · Oct 21, 2013

Goliath said:
Thanks for the reply. I'm not sure that it's poor circulation as I have the pump running 8hrs/day. There are 3 returns at 45 deg angles that make the water rotate in an anti-clockwise direction pretty well.

It did rain last week, and I have not checked the levels since. Could it have grown that fast?

Oh, yeah! 7.6 FC at 45 CYA probably dropped to zero in three or four days. Add the organic load from whatever the rain washed in, and you've got all the ingredients.

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Goliath · Oct 22, 2013

Why would the FC drop to 0? I was not adding any chlorine or derivative to get to the 7.6. That FC level has been fairly consistent over the last month. It is high, but I have not used the pool. The pump is running 8 hrs/day with SWG at 60% and it stays at 4 (hot days) to 7 now that it's getting cooler. I was going to lower the SWG % to get it to 4% until I saw the algae.

Are you saying the rain (which was only off/on for 1.5 days) dropped it to 0?

duraleigh · Oct 22, 2013

Why would the FC drop to 0?

Two things consume chlorine....sunlight and organics in your pool.

Chlorine is constantly being consumed in your pool so must be constantly replenished.

Richard320 · Oct 22, 2013

Goliath said:
Why would the FC drop to 0? I was not adding any chlorine or derivative to get to the 7.6. That FC level has been fairly consistent over the last month. It is high, but I have not used the pool. The pump is running 8 hrs/day with SWG at 60% and it stays at 4 (hot days) to 7 now that it's getting cooler. I was going to lower the SWG % to get it to 4% until I saw the algae.

Are you saying the rain (which was only off/on for 1.5 days) dropped it to 0?

Oops, missed that you have a SWG. So the FC probably didn;t drop that fast naturally, unless of course the water is too cold and the SWG shut down.

So it's still organics or poor circulation. I know I have a spot where all the leaves settle and I haven't been able to aim the jets to completely eliminate it. That's poor circulation. You may have a dead spot somewhere, too, especially if no one's getting in and mixing it up.