Year Start Up / Dirt or Algae?

[Shani]

Hi Folks,

Hope everyone is doing well in getting their pools started for the year. I got a new pool installed last year, went with a salt water pool with SWG.

Cleaned all the debris out of the pool, got the pump running this weekend. Ran my initial test and got the following:

FC - 0.31
tCl - 0.36
pH - 7.4
TA - 110
CH - 183
CYA - 49
Instant Salt - -1800 (Read from the AquaTrol)

After reading the AquaTrol manual I setup the SWG to run at 100%, added the recommended pool salt, and added about 900mg of dry Stabilizer (from PoolMath) and left the pump running 24/7. Today the pool is perfectly clear, so I ran another set of tests:

FC - 3
tCl - 3.31
pH - 7.5
CYA - 62
Instant Salt - -2100

I am still running the SWG to get the Cl levels up to 5 - 6. I had a couple questions:

1) I am seeing what looks like dirt at the bottom of the pool, I can sweep it, it clouds. We do get a lot of dirt in this area. After reading some articles on here I am questioning if this is actually Algae. Is there a way to determine one way or another. The pool is a bit cold to get into to feel the substance yet as I am also in the process of fixing some plumbing leaks for the heater. I attached a picture of the substance.

2) According to the Aqua Trol manual the CYA and Chlorine Levels are much lower than recommended by TFP. Picture from manual attached. Just trying to understand why the difference. Would it have anything to do with the low salt generator?

Thanks for the assistance.

 

[Richard320]

To just answer your question and not digress, run Overnight Chlorine Loss Test That will tell you if there's organics consuming the chlorine. Note that the SWG needs to be off for this, the pump needs to stay on, and the FC level should be somewhere near 10. So you'll want to add some bleach to get that FC up. Give it time to mix before you do the after-sunset test.

 

[Shani]

Hi Richard,

Thanks for the info. Bought some liquid chorine and put that in the pool will get the levels up and do some testing.

 

[Shani]

I ran the OCLT, results from last night ~10pm:

FC - 8.55
tCl - 9.88

I left the pump running but turned off the SWG. Results from this morning ~5:30am:

FC - 8.37
tCl - 9.77

From my understanding reading the info that small amount of loss is acceptable and I wouldn't have an algae issue. I will keep attempting to clean the bottom and see if the filter can clean this out. Wanted to follow up my second question above:

2) According to the Aqua Trol manual the CYA and Chlorine Levels are much lower than recommended by TFP. Picture from manual attached above. Just trying to understand why the difference. Would it have anything to do with the low salt generator?
Manual Shows:
- Free Chlorine: 1 - 3
- CYA: 20 - 30

Thanks again!