Starter Pool Help!

[leveckio]

Alright, I'm new here, but am familiar with water chemistry from keeping fish for years...this is proving far different in many aspects. We decided to purchase a small soft side vinyl pool from Costco to make sure we could keep up with the water chemistry and maintenance before plunking down a considerable amount of money on our dream pool. That said, we have been experiencing a difficult battle with what appears to be algae.
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Background...we purchased this pool last season and did a terrible job of closing it up for winter...lesson learned. It was super ugly, but we were able to keep it clear and algae free for the last couple of months before closing. We closed it for good right around Labor Day.
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Fast forward to this year, we opened the pool to find a nasty muck of a mess! We dropped this and that in there and got it relatively ready but didn't know how we did it...local shops weren't much help. Memorial Day weekend it was cloudy but levels seemed okay so we swam... a few drinkers may have relieved themselves and its been a battle since then. The filtration system, as of the day after Memorial Day has been supplemented with two Intex cartridge filters to try to remove the algae prior to seeing the sand filter...pressures stay normal in the sand tank. Daily, since 6/2, the cartridges are removed and replaced with the previous day's cartridges after getting a rinse and chlorine bath in 5g of water and 4oz of 12.5 SH.
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Found this site and decided a good test kit was necessary and started testing and logging following some tables in the test kit booklet. Here are what we have done since the test kit arrived:

Pool Notes:	Pool Type	Volume	Filter	Test Method	Solar cover removed 6/1; white pine tree nearby drops lots of debris
AGP	Vinyl	6,500g	Sand	1800GPH	Taylor Liquid
Date	FC	TC	CC	PH	TA	CH	CYA	CSI	Temp F	Notes:
6/2	-	-	-	-	-	-	0	-	-	2lbs of Stabilizer
6/3	6	6	0	7.8	130	350	60	0.6	80	-
6/4	2	2	0	7.4	125	350	60	0.1	77	8oz shock/16oz MA
6/5	10	10	0	7.3	125	350	100	0.07	79	removed chlorine floater
6/6	10	10	0	7.4	130	325	100	0.12	78	16ox MA/aeration
6/7	8	8	0	7.2	110	325	100	-0.15	74	24oz MA
6/8	6	6	0	7.3	110	325	100	?	74	24oz MA
6/9	3	3	0	7.2	90	325	80	?	76
6/10	10	10	0	7.4	100	325	80	?	72	added clarifier, put solar cover on due to forecasted rain and lower temps
6/11	7.5	7.5	0	7.5	90	325	80	?	75
6/12	7.5	7.5	0	7.5	90	325	90	?	74	1.25g of 12.5 SH
6/13
source water	0	0	0	7.6	200+	300	0	n/a	n/a

What I really have a hard time wrapping my head around is why the FC is always the same as TC with a continual algae problem? I now know the CYA plays a role as well as pH, but this has been my project and my GF would prefer to swim while I work on the house and not the pool! LOL
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All help is appreciated!!!

 

[HermanTX]

Welcome to TFP
It is great that you are keeping records of your test.
We all use the PoolMath app that keeps the data and helps you make the right decision on amount of chemicals to add. It is $8 per year and well worth it.

While the K2005 is a good test kit, it lacks the FAS-DPD needed to properly test for FC and CC. You can purchase this separately at tftestkits.net.

Your CYA is declining and that only should occur if you have physical drained pool water and replaced with tap water. Did that happen? Or are you having a testing error? It is concerning that your CYA was 100 or higher so you may need to drain 50% of your pool to lower the CYA.

You are fighting a uphill battle with high CYA, low FC because algae will continue to hide and grow.
You need to read the SLAM Process and only use liquid chlorine and stay away from pucks and granular shock. Also do not use algaecides. They all can make matters worse.

You seem to be using a lot of MA for a small pool of 6500 gals. What strength MA are you using?

We are here to help. It is also good if you can read the following
Pool Care Basics
FC/CYA Levels

 

[leveckio]

Thank you for your response!
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I will check that app out, thanks!
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I have ordered the FAS-DPD. It should arrive Thursday or Friday.
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During some vacuuming I was discharging the nasty algae filled water and would then top the pool back up so that’s what I attributed the drop to.
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I SLAMmed the pool last night before posting with 1.25g of liquid sodium hypochlorite to bring the levels up to 35ppm based on a calculator from Taylor.
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The MA is what I bought from my local pool store and from memory is about 30%...I’ll have to check later when I am home. I attributed the slow decrease of TA to the alkalinity and super buffered water, which is something I learned from keeping fish that the water in our area is insanely hard and pH is difficult to manipulate.
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I’ve read both of those article sand found it very interesting to read about the CYA impact on FC. The calculator recommended the FC level to be 11. We may break down and drain the pool, but that is going to bump the TA right back up there…always something to learn!
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Omg…apparently I didn’t hit submit on this… ugh

 

[MITBeta]

SLAMing is a process, not a one time event (SLAM Process).

The calculator recommended the FC level to be 11

This is a maintenance number for your CYA level in a clear pool. Your SLAM target will be much higher. You would be better served to drain at least half the pool to get THAT CYA number down to a manageable level.