Befuddled and Bewildered ----can't clear haze

[brigidc]

Help.
We did not cover our 27 ft round abg pool this winter, so started with a green swamp. We cleared all the debris we could find, got test results from the pool store on @ May 12:
FC 0
TC 0
ph 8.0
TA 90
CH 200
CYA 50

Also, we have scale on the vinly liner sides and I presume the bottom too.

I ordered the FAS-DPD and CYA tests to supplement the basic kit we already had, worked on getting the ph in range with muriatic acid while waiting for the test kits to arrive, then began shocking on May 20th. The algae quickly turned to bluish gray and I backwashed a number of times in the days since then as it filtered out. However, I have been shocking for 10 days now, using only liquid bleach, and cannot figure out what is going on. The water is blue but does NOT appear to be getting clearer each day---if it is clearing any it is very very marginal. CC has gradually come down to .5 or less (from a high of 1.5) but FC loss overnight continues to be between 2.5 - 4 and during the daytime it was rare for the shock level to hold. The ph is now continually low so I am adding Borax almost every day (5 out of the last 6 days). The TA has gradually risen and is now at 120. The scale has 'softened' somewhat to where I can brush it off easily with my hand where I can reach, but it is much harder at the winter water level line. Does the lowering ph and increasing TA have anything to do with the scale dissolving?
The CYA level has come down from 50 to 30 (after 9 backwashes) and I put some in a sock to dissolve last night, then the rest in another sock today---most of it is dissolved.

As of this morning I am out of the titrant for the FAS-DPD test, so can't test reliably until new comes in. My last full test results this morning were:
FC 13
CC .5
Ph 7.3 -7.4
TA 120

I don't have the CH test.

I won't retest CYA until all is dissolved and then maybe let another day or two pass? or am I okay to restest for that once the sock is empty?
FC last night was 16.5 or 17 and I did not add any after that test.

I've added borax today and turned the return to where it will aerate.

I vacuumed once early on and brush the sides and bottom daily, check the filter pot and clean the skimmer sock daily.

Is this normal to take so long to clear?

Thanks for any insight you can provide.





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[frustratedpoolmom]

Hi and welcome.

This is perplexing. It sounds like you have been doing everything right. So lets throw some ideas out there.

Sand filters can take a while to clear up a bad algae bloom. It would be helpful to have more info on the pump/filter, to make sure it's the right size for your pool.

You can try the DE in the filter trick, that reports good success. Read about "how to" in Pool School.

How often are you backwashing - because the pressure indicates it? Because sometimes "dirty" sand filters better, and if people are backwashing too often it actually takes longer to clear up the cloudiness. This is also why the DE helps with clarity.

Also, are you certain there is no more debris at the bottom that could explain the FC demand? You said you vacumed once... You could try leaving the pump off overnight, letting everything settle and then vacume to waste once more.

As for the scale, low ph should help with that. I would be very careful adding borax AND aerating, as both will Raise your PH and I would leave it where it is right now. 7.3-7.4 is not worth worrying about - in fact at that level the bleach should be more effective.

That's all I can think of right now, hope this helps, and let me know if I missed something or you are confused.

 

[JasonLion]

The most likely possibility is lots of muck still on the bottom of the pool. Try vacuuming blind as much as you can.