1st Timer with TFT

KatyTXPoolOwner

Well-known member
Jul 18, 2015
102
Katy TX
Frustrated pool owner here...... (and fairly new to TFP)
FC 5.5
CC 0
TC 5.5
CYA 100
TA 140
CH 300
PH 7.6

I've been battling algae and it won't seem to get better. I took apart my filter (Quad DE 100) and cleaned it and recharged it a week or two ago and thought pool was good. But the algae is back. Mainly on the sides of the pool.

Should I lower CYA by replacing approx 45% of the pool water as TFP Pool Math suggest? I've not done that yet ( 2 year old pool) so I'm a bit leery.

Previous readings from TexSun said CYA was at least 151+ but after a hard rain they said it fell to 40. They said CYA sits in the top layer of the water and it drains out the overflow, and they suggested putting a hose at the bottom of the pool to push the CYA out of the overflow like a big rain would do. Not sure if I believe them or not, which caused me to get the TFT 100.
 

KatyTXPoolOwner

Well-known member
Jul 18, 2015
102
Katy TX
Trust your test kit. If your concerned about your pool surface you can drain and refill in stages.
Thank you.

Do you suggest replacing the water enough to get CYA down to 50 or so?

If so, does it make sense to put the garden hose at the bottom of the pool to push the water out through the overflow drain?

Then, once I get the CYA down to 50 or so, shock the pool to eliminate the algae?
 

txnole

LifeTime Supporter
Aug 18, 2014
544
Amelia Island, FL
CYA test isn't reliable at 100+, unless you conduct a diluted test. Your CYA might be 100, 150, or 300. Do a diluted test, if possible or Replace 25+% and retest. You definitely need to lower to give your FC a chance. In the interim, raise FC per the chart. You may be a SLAM candidate once you get CYA under control.
 

MarianParoo

Well-known member
Aug 16, 2014
4,615
Northern IL
The tarp method is for vinyl pools to stabilze the pressure on the liner.

By using your ovefill drain, it will take a lot more than 45% refill to get your levels down. It is better with your gunite to just go for it. You might want to do another check of CYA next time it's sunny before deciding how much to drain as a diluted test may give you a more realistic CYA "now" value. Here is a link as to how to do a dilution method for CYA over 90+. See point #9:

Pool School - CYA
 

KatyTXPoolOwner

Well-known member
Jul 18, 2015
102
Katy TX
I ended up draining about 7000 gallons (~30% of total pool volume) through the Waste setting on my filter valve. (On a side note - in that process I think I figured out the pool builder did not run the suction lines back to the equipment pad correctly. I could not use the Main drain suction only - a skimmer was always draining).

I also "Overflowed" approximately 9000 gallons out the overflow drain (garden hoses in the pool until the water rose enough to exit out the overflow drain and let that run awhile).

I tested CYA tonight and my best guess is 65. It's tricky seeing the black dot or not but I'm going with 65 or so.

I'm going to check again tomorrow to see what it looks like then. Wish me luck (and thank you for the help!)
 

fajitas21

Well-known member
May 16, 2016
65
Orange, TX
Hello from Orange, which is about 2 hours from Katy. I was in the same situation as you were, my CYA levels were 100+. The FC needed to maintain an algae free pool at this CYA is about 8 - 14. I was able to do a drain of 45% of my pool to get my CYA down to a manageable 70. 50 is ideal, but 70 (or 65 in your case) is very manageable. A couple things to note.

1. If you backwash to dump water in the future, make sure you can safely run your pumps even after your water line goes below the skimmer line. Depending on the case, it would be like running a boat motor without water to cool the engine. I ended up renting a utility water pump from home depot and dumped it that way to be safe, while I left pumps off.

2. We get a lot of rain. You, living in Houston, CERTAINLY know what I mean. The auto-drain + rain will slowly get rid of CYA, but it takes a while. For example, last months rains managed to get me from 90CYA to 70CYA, and it was a LOT of rain.

3. Pool store CYA tests pretty much cap @ 100, so if it's 100, or 500, they say it's 100. Learned this the hard way.

4. Check ladders, behind light fixtures, and behind water jets for algae that might be hiding to come back and re-grow when you let your guard down.

The drain in my case made it much easier to manage the levels of chlorine needed, and reduced the cost, since there was less chlorine needed as a ratio of my CYA levels. The pool math calculator should help you figure out what you need, don't forget about the bottom of the calculator that wants your pool type, and chlorination method.

Good luck!
 

KatyTXPoolOwner

Well-known member
Jul 18, 2015
102
Katy TX
Thank you, fajitas21. Old fraternity brother of mine is from Orange (went to LCM) and I've been there many times.

Regarding running the pump with the water line below the skimmers, I think I should be able to do that if my plumbing was done correctly - let me explain. I have 2 main drains in the deep end (7') at the bottom of the pool, in addition to the 2 skimmers on opposite ends of the pool. Yesterday I tried to turn the valves at the equipment pad suction side in such a way that the pool water would only drain from the main drains and not the skimmers. Unfortunately, when I turned the valves that way I was still sucking water from the main drains (I assume) AND 1 of the skimmers. I thought the suction pipes were plumbed as follows: 2 main drains tied to 1 suction pipe back to equipment pad and 2 separate skimmer pipes both going back to equipment pad. Of course, all three of those pipes meet above ground through a couple valves and into the single suction pipe into the pump. All that make sense? I may not be arranging the valves correctly but I think I am.
 

fajitas21

Well-known member
May 16, 2016
65
Orange, TX
Others who know more about the plumbing element may chime in, but sounds like you got it dialed in right. And I also graduated from LC-M in 2000. These guys on the site will get you fixed up, they are great.