CYA test confusion

[Dippa]

Hi Everyone
i have just finished the SLAM and ready to balance the water. I had trouble with determining the CYA with the SLAM and erred on the higher value. I'm retesting and get values between 50-80 and it's driving me mad. If I had to pick a number I would say 60 or 70. My FC is down to 6 so I feel it's close to algae problems and need to move forward.
My Taylorsk2006c test Results
13dec. 13dec. 12dec. 12dec. 11dec
4.30pm. 10.am. 6.00pm. 12.30pm. 5.00pm
FC. 6. 6.5. 7.5. 8.5. 9.5
CC. 0.5. 0. 0. 0. 0
TA. 60. 60. 70. - 50
CH - - 220. - -
pH. 7.4. 7.8. 7.6. 7.4. 7.4
CYA. - 60? - 60/70. -
phos 200ppb(aquacheck)
salt no test but assume approx 4000 will test tomorrow at pool shop.
Ihave been adding a kg of buffer each day to increase TA slowly.
Im brushing every day and filter on high setting for 8 hrs.Still having trouble finding the right ORP for SWG but may need to manually turn it on to generate FC as it hasn't kicked in the last 2 days hence the drop in FC as we have had sunny days.
I am reluctant to add any CYA to get to 70 as recommended for SWG as I want to be first certain of the CYA level I have now.

CYA level ???? So target FC???
Any advise from the experts?
Should I just bump up the FC say to 9-10 either with SWG or liq ch before I get into algae problem.
i will check tomorrow morning if FC has dropped and CC raised over night.
Thanks

 

[kimkats]

Here is my way of doing the hated CYA test!

-Stand with back to sun, tube held at waist
-pour some mix in the tube
-GLANCE in tube, look away, GLANCE one more time, look away. IF you can still see the dot using a GLANCE add more water. Repeat until you do not see the dot with a GLANCE.

If you stare at it you WILL see the dot LOL

If the water is between 60 and 70 call it 70 and add FC to that.

I hope that helps.

Kim

Adding tiny bits of water helps as well.

 

[Jezza]

Firstly good to see things looking on track Dippa and I assume that there is no further sign of algae?

I think that your overthinking your CYA testing. It is certainly the most difficult to master but believe me you get better and more confident at making a call.

Are you using the averaging strategy (putting the solution back into the little pourer/squeezy bottle and redoing the test a few times to get an average) or getting another person to measure and cross check results. If your result is somewhere between 2 whole numbers round up to the higher number and then you'll be covered.

By what you are saying it sounds like your CYA level is 70 in which case your minimum is 3 and target 5 as per the CYA/Chorine chart. You could aim for marginally higher say around 7 for insurance but you don't want to get it too much higher or the sun will burn the extra chlorine off a lot quicker which can get expensive and wasteful (either because you are running your SWG for longer periods or adding liquid chlorine). So maybe marginally bump up the running time of your SWG and test daily and then toggle with either your SWG run time or chlorine output level. What you are looking for is when your FC holds relatively steady- keeping in mind that higher bather load and hot weather will increase the demand on your FC. During these times I often add a litre of liquid chlorine to help my SWG out.

 

[Dippa]

Hi Kimkats
i have used your method. I thinks it's the best way but still get variation.i will keep trying. Thanks

 

[Dippa]

Hi Jezza
i test the CYA both ways. I do it several times reusing the solution and also get some one else to test. I only test on bright sunny days as the results vary dramatically if cloudy. I will test again tomorrow and check FC and CC for any overnight changes.
Since the SLAM the algae has been abscent but I'm not sure if I spotted a very very faint green on a section of wall late today. Hopefully it was dust as we have had very windy days..... I worry as I used to get green around the FC 4-6 before SLAM.
Will see what results I get tomorrow and see if anything comes off the wall when I brush....
thanks

 

[duraleigh]

1. With practice, the CYA test just gets easier....it's that simple and don't overthink your results....you have some wiggle room.
2.

Ihave been adding a kg of buffer each day to increase TA slowly.

What is "buffer"? More importantly, you should not be increasing TA.....leave it alone.

3. It appears your SWG is increasing your FC and it is already too high. Shouldn't you be dialing it back to the suggested FC levels in Pool School?

4. Any hint of green anywhere is not a good sign and your first reaction should be to brush it immediately. Algae multiplies very quickly so brush it up into the chlorinated water flow and it will quickly be killed. Don't wait 'til it's convenient if you even think you see green.....brush it now.

 

[Dippa]

Hi duraleigh
sorry, here "buffer" is the common name for sodium bicarbonate.
I was aiming for a TA of 70 as it was down from 20 last week
my SWG hasn't generated any FC in the last 2 days and it's dropped from 9.5 to 6 so I don't won't it to drop less than 5. It will be a sunny day tomorrow so I probably loose 1-2 FC.
i did brush walls before it became night.
Thanks

 

[duraleigh]

I'm still gonna' badger you just a bit, Dippa, not to pick on you but to make sure you have a good grasp of what we teach.

it's dropped from 9.5 to 6 so I don't won't it to drop less than 5.

What does pool school tell you your normal range should be? Why are you not starting the SWG back up when you get to a level you want to be......that's what it is supposed to do. What has your SWG percentage setting been this past week? Is it still the same?

Leave your TA where it is and check it weekly.

Leave your CYA where it is and check it weekly for a couple of weeks and then monthly.

Monitor FC daily and adjust SWG percentage to hold a constant FC.

 

[Casey]

Quote from SLAM thread....

I left the pool as I finished the SLAM. I got my brother to check the pool when he could and do a FC each time. I also set the filter for 10hrs a day on high speed (usually 8hrs). Instructed him to brush when he could. It looked good when I got back. FC had dropped below my target 2 days before returning so I got my brother to put in 3lt of liq ch to bump up the FC just to be on the safe side.
Now will try to balance water and get SWG to the correct setting. I suspect I will just have to try and see.
Hoping that I have finally got rid of the green monster.

Dippa, you have a SLAM thread going and you left 2 weeks ago and I asked you if you finished the SLAM? You stated that you left the pool in the care of your brother.

If you are saying now that you may be seeing green, you did not finish the SLAM and you need to perform an OCLT and see if you are losing FC and brush the whole pool.

It is very important to finish a SLAM. If you continually stop before it's all dead, it will continually come back within days.

 

[duraleigh]

Wow! A perfect example of why we discourage members from starting multiple posts. I had no idea of the past history here and it would've modified my advice.

Few of us frequent posters have the time to chase and try to piece together multiple threads.

 

[Divin Dave]

There is no need for this test to be so confusing. Follow the instructions for testing, and there are even videos of it. The test accuracy is +/- 10, so its likely not going to repeat with regularity with multiple testing of it. This accuracy largely due to varying degrees of poeples eye sight, plus the difference in available light at the time of testing.

Since this is the case, then an average number is the best practice to use. It cant be more simple.

Want my advice? Test the CYA, then pour the solution back into the mixing bottle and test again. Do this at least 5 times (or however many more you have patience for) and then average the result. Round UP to the nearest 10 and your done and no need to worry about it.

 

[Dippa]

My apolagies for creating confusion with this tread I thought it would need a new one. I will stop using this one. Is it ok to go back to the my previous thread?
But just to clarify...
I have seen the CYA videos and read the instructions it's just the variation in the results that had me concerned I was getting it wrong. I will just average out and round up to nearest 10 as Diving Dave points out. Thanks.
As for the OCLT it was ok after the SLAM.This morning the results were good FC 5.6 and CC 0 (only a FC drop of 0.4 overnight) and no green with brushing. Maybe just dust last night.
Again sorry for the confusion and I really appreciate all the help and advice given by you (all)