A few questions from an "older newbie"

Jun 22, 2008

I own an IG "low-hung" 18 x 36 pool (est. 28000 gal) with a sand filter system. I just received my TF-100 today and my readings are...

Temp - 86

My water is crystal clear. I use liquid chlorine and I also have an auto chlorinator but I have turned it off as of two days ago (seems like they aren't a good idea from what I have read on this site). I know the chlorine is high, not sure if this is why the T/A is so high...? I started bringing the chlorine up because I am planning on shocking the pool but wanted to run the tests of the new kit before I shocked it.

My actual question is this. I have a problem with a yellow stain-like substance on portions of the both floor and walls of the pool. It started last year and will come off with a brush. I shocked the pool a couple of times last year and it seemed to have little effect. When we opened this year everything was fine and remained that way for the first month or so, now - right back to the same game. I am not sure if this is a form of algae or some kind of metal staining but it is getting VERY frustrating. I have even considered that it may be pollen, but I think it is too much and it "grows" even on a calm day when we have the solar cover on. What is the best way to tell what this is? Any help would be GREATLY appreciated.

Please let me know if I have left any important info off of this post and I will answer quickly as I am planning on shocking the pool tonight as a first step.

Thank you for your help and this resource.
Jun 22, 2008
Thank you Joyce.

You are right, I forgot the zero. The alkalinity is actually 350 - very high. I just checked it again and it came out at 330. Sorry for the mis-placed decimal pt. and the slow reply...too many projects going on at once I am afraid...I look forward to your reply.

Just as an update - I have upped the chlorine, vacuumed out the pool and now just brushed it again. It definitely seems like an algae I think as it is coming up when I vac it or brush it...

Thanks for your help!


Platinum Supporter
LifeTime Supporter
May 14, 2007
Detroit Burbs
You seriously had to drop in 33 drops to test T/A?
Man I thought mine was high at 20 last month.

I'm no expert, so take this for what it is, which isn't much.

Get some Muriatic acid to lower the Ph to like 7.1, either make or buy a water feature that will create bubbles, and keep doing this for a week or so.

I think you have enough chlorine in, but I don't really know.

Check out the pool calc to help with quantities. http://www.poolcalculator.com/


TFP Expert
LifeTime Supporter
May 30, 2007
South Carolina
Here is the link to the full instructions for lowering your TA (as krcossin said): category/pool-school/lowering%20total%20alkalinity

Have you had your fill water tested?

Is your pool in full sun?

It would be helpful if you list your location (city and state) in your profile. Also, add all your pool and equipment info to your signature so that it automatically appears with each post.

Just go to the top/left of the page under the TFP logo and select "User Control Panel". Select "profile" and you can get started.

Someone will be along to talk about your algae issues.
Jun 22, 2008
OK - here's the latest.

My alkalinity has always tested fine before this. I emailed the TF-100 people because it seems like the kit might be a little defective. The drop from the R-0009 is quite small - (about half the size of a "normal drop"). I just took my water into my local pool store and they tested my alkalinity at 150. So I emailed the TF-100 company and then noticed on some previous posts that they were having some trouble with their dropper tips. Maybe this is a residual effect? I will wait to see what their response is...

Thank you for all of the help so far. It has been very informative. I have changed my signature as suggested. Any other help or suggestions will be appreciated!

Thanks again...
Jun 22, 2008
I found this post from waterbear on another forum. I hope that this helps.

What I question is their advice to drain and refill. This is usually done when the CYA (stabilzier) levels go too high from using stabilized chlorine (dichlor or trichlor). This can lead to algae outbreaks in what otherwise seems to be a balanced and properly sanitized pool.

Most of the 'yellow' products (yellow out, mustard master, etc) are either bromine or inorganic ammonia based and require that the pH be at about 7.8 for best results (to form either monochloramine or bromamine, both of which are 'eaten' by the algae and then kill it). They are ususally very effective. After their use it can sometines take a lot of chlorine to get your pool to hold FC.

Banish is a coper based algaecide. Copper is somewhat effective against mustard algae but is usually better as a preventative. Polyquat based algaecides are, IMHO, a bit better against mustard. Just be aware that once you add copper in your pool it will stay there. It might no longer show up on a copper test but that means it has fallen out of the water as a stain and can redissolve if the pH drops. If you do add copper be careful about your shock levels. High amounts of chlorine can cause the water to turn green if there is copper present, expecially if it is non chelated or if it has stained and then redissolved!

Sometimes just getting your chlorine level to about 15-20 ppm (depending on your CYA level) and HOLDING IT THERE UNTIL THE ALGAE IS GONE can be effective but this will require you to be adding unstabilized chlorine several times a day and testing the chlorine levels yourself and this process can take several days to complete.