Crystal Clear to yellow/green from Cal Hypo???

[EGVPoolDude]

Hi all:

I have a 28,000 gallon concrete pool with fiberglass walls. After turning an algae fest at the beginning of the season to a crystal clear oasis, I got all my numbers perfect with the exception of CH. I had some interesting stains on my stairs, and since that was the only number that was off, I decided to switch to Cal Hypo from Bleach just to get the number into the acceptable range. After using cal hypo for the last 3 weeks, my pool has gotten cloudier and cloudier and now is on the verge of this light green/yellow color. Every time I add cal hypo (tried direct into skimmer and also diluted using 5 gallon bucket of pool water before distributing into deep end), the next day I see yellow deposits/streaks all over the pool. It vacuums up easily enough, but comes right back the next day. Are these just calcium deposits? Are they going to go away once I switch back to bleach? Should I just forget about getting my CH numbers up since I had a crystal clear pool to begin with?

TA: 90
PH: 7.4
CYA: 45
FC: 6.0
CC: <0.5
CH: 125 (started at 90 prior to switching to cal hypo)

Thanks in advance!

 

[Casey]

Welcome to TFP.

How are you testing your numbers?

Are you able to pass the Overnight FC Loss Test?

I could be wrong but the yellow looks like algae to me. I could be wrong... Lets see what others think too.

BTW, the pool looks really nice!

 

[EGVPoolDude]

I am inclined to agree with you since the pool is just straight up green this morning, I'll post a pic later this morning. Not sure how this happened since I'm usually good about adding chlorine every day.

I use the Taylor FAS-DPD kit like the most of you guys. Additionally, I just did a OCLT last night and I only lost .5 ppm. CC still <0.5 ppm. I just wanted to see if this was a metal problem or algae before I did a SLAM. Filter runs 12 hours a day and I haven't really been back washing more than normal, probably about once a week when the pressure increases to 15-16 psi from my baseline of 13psi.

Thanks for the comment, looks much better when it's clear!

 

[EGVPoolDude]

Pic of pool this morning, looks like I have some SLAMing to do.

 

[chem geek]

If it's clear green, not cloudy green, then it could be metals (have you used copper-based algicide or a copper ionizer before?). If you lower the pH and the green fades, then it's likely metals.

 

[EGVPoolDude]

Thanks for the reply.

I have not used any type of copper based products since I bought the house 2 months ago, just been following BBB religiously. The only thing that has changed is the switch to cal hypo for the last couple weeks, and I had to dump muriatic acid in the pool about a week ago since a pool party with splashing kids raised my PH to 8.0.

If it is metals, what is the solution here? Sequestrant?

 

[JasonLion]

If it is metals, lowering the PH will probably make it go away for now, but it is likely to come back the next time you add cal-hypo. Using sequestrant is more dependable, but also rather more expensive.

Iron tends to make that yellow/green color. Iron is fairly common in well water, rare but present occasionally in municipal water.

 

[EGVPoolDude]

Well, looks like I am shutting down the cal hypo experiment and going back to good old bleach. I'll dump some more acid in the pool tonight and see what that does for water clarity. In regards to the calcium hardness which is why i made the switch originally, is it a huge deal if my CH is still sub-200?

Thanks for the help!

 

[JasonLion]

As long as CH is below 350, using cal-hypo is normally fine. In some cases cal-hypo can make the pool cloudy, normally only when TA is high. If your problem is indeed metals, bleach is like to have the same effect.

Metals can get concentrated in the water by evaporation. It is possible that the iron level has been building up for some time and only just got high enough to have any effect.

 

[Butterfly]

I also agree that you should do an OCLT to rule out/in organics.

Get the pool clear and then increase the CH to recommended levels.

from Pool School:

CH - Calcium Hardness

Calcium hardness can be raised with calcium chloride or calcium chloride dihydrate. They are available in some areas as Peladow, Dowflake, Tetra Flake, or Tetra 94, often sold as a deicer by hardware stores, and some big box stores, in colder climates. Pool stores will carry either calcium chloride or calcium chloride dihydrate under a variety of names, including Hardness Plus, Balance Pak 300, Calcium Hardness Increaser, etc. Calcium products should be spread across the surface of the deep end of the pool.

Welcome to the forum

 

[EGVPoolDude]

Passed another OCLT this morning from 6ppm to 5.5ppm with no CC. Looks like this is a metal issue. I dumped acid in the pool last night, it's still green/yellow, and the PH is now lower than 7.0, do I not have a risk of metal components corroding? I have pointed my returns up to help with aeration.

Additionally, I have my pool vac going throughout the pool, are metals small enough to go through the sand filter? I'm not sure why there has been no progress whatsoever...

 

[EGVPoolDude]

Apparently it was algae... ughhh... I guess I was being a little lackadaisical with my FC levels necessary for my CYA. The only thing I could think of was that bleach increases FC right away while cal-hypo needs some time. I would usually add my sanitizer at night shortly before turning off my pump. Anyway, I have made progress during the SLAM process, should be another day or two, I've been brushing and vacuuming to waste at 5:30 each morning.

Thanks all!