AFter bleach gets rid of green - when is it safe to swim?

Jul 27, 2007
Hello... New to forum and pools too. Grandma with 7 grandkids (ages 7-13) that suddenly love to come to Grandma's house since there is a new pool in the backyard. LOTS of rain lately and the HTH method failed and suddenly had a pool full of pretty green water with baby mosquitos swimming in it. (Happened so fast!) Being a google freak helped and led me straight to TFP.

current approximate readings (sorry - only have HTH test strips right now until payday)
TH 400
FC 1
pH 8.4
TA 200
CYA 15

Have spent the last two days reading all your stickies and prior postings. Got some great help from Waterbearer last night. Used the pool calculator to find out I needed 31 oz. of bleach and dumped it in last night. Woke up this morning to a very clear pool. This morning the TA was high and the Ph was high, but everything else was within limits. This afternoon - the FC was 0 again. Added more bleach. I just read that the sunlight eats it... and I need to keep adding it. I also realize that I need to replace some of the water (varying opinions there about how much) to help get the Ph and TA back to normal. New filter, brush and vacuum today, more bleach tonight.... keep on doing it with patience... no problem. Also looks like I need to add muriatic acid... will do that. How long do we have to wait to swim after muriatic acid is added? Is it safe to swim before I do that? (not purchased yet.)

TODAY - It's 83 degrees outside and next 4 days in the low 90's... and I have 5 of the 7 grandkids here spending the night and they want to swim. The pool LOOKS clean... no bugs visible... but is it safe to swim yet? Does everything have to be in balance before you get back in the water? Are there time limits after adding BBB before you swim?

Thanking you in advance...


Well-known member
Jun 18, 2007
Charleston, SC
You shouldnt need to replace your water to help with your TA and PH.

Put muriatic acid in to lower the pH, which you should do pretty soon, your pH is very high. It will also drop the TA down a little. You can continue to use muriatic acid to drop pH and TA, then aerate to bring the pH back up. Repeat process, and eventually your TA will be where it should be.
Jul 27, 2007
Thank you... I had read about the muriatic acid and the pool calculator tells me how much.. I will get some tomorrow.

But what I need to know most is IS IT SAFE TO SWIM without the pool being completely balanced?
I have 5 kids here right now begging to swim because the pool LOOKS fine... They will be gone tomorrow and I can start over because they won't be back till next weekend... but I sure don't want to make anyone sick...


The Mermaid Queen

TFP Expert
LifeTime Supporter
Mar 28, 2007
Northern KY
If they are young enough to drink the water, I would keep them out for now. Also the high FC and high pH might irritate the eyes a bit (I know low pH irritates, not totally sure about high...)
If they are older kids, I would probably say ok, but have them rinse well upon exiting the water!
Welcome to TFP!
Jul 27, 2007
Thank you

Thanks again... and thank you for the welcome! The kids are all old enough I think... the youngest is an extremely smart seven. With good warnings and close supervision... and a shower after... We're gonna go ahead swimming. My best friend has a big pool and she says her grandkids have jumped into it when it was green yuck... and they all survived. But somehow that wasn't enough reassurance for me...

Thank you all for this great forum... I know I will be studying it for a long tome to come.

You are doing GREAT! Soon you will be helping other newbies on here with their pool problems! Just wait a bit and you will see it's true! Great job!


TFP Expert
Platinum Supporter
LifeTime Supporter
May 7, 2007
Silver Spring, MD
The most crucial numbers for swimming are the free chlorine level and the PH. As long as you can keep the FC level at two or above and the PH between 7.2 and 7.8 then swimming should be fine. Both of these can be done quickly.

It can be a bit tricky to keep the FC high enough given how low your CYA is. With low CYA, sunlight will burn off your chlorine fairly quickly. You will probably need to add bleach twice a day, midday and evening are best, till you can bring the CYA level up. Longer term I would aim for CYA between 30 and 50. That will help you hold your FC level more easily.