BBB toxic to grass?

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D

dsm

0
Jul 3, 2010
61
Double Oak, TX
Don't know where else to post this.

I am in my 14th season as pool owner and 3rd season in BBB. Pool looks great, and I'm very satisfied with the chemical management of the pool. But, as my topic suggests, I have a new conundrum.

I started noticing this last season. My IG pool has an overflow spout that drains into the yard downhill about 15 ft. Starting from the exact location of the end of the drain pipe I have grass kill that extends 15 ft, over an area that is approximately 15'x6'. I also noticed significant yellowing of the grass in the area where I backwashed my filter this spring - so I am confident that something in my pool water is killing this section of grass in my yard. (The backwashed section of my yard recovered after about 10 days.)

Anyone know what combination of chemicals in BBB is killing the grass at the end of my overflow drain pipe?

Thanks
 
I have salt and my grass seems to love it, grows more there than anywhere else. I'd bet it's the DE, not positive but since it filters such fine particles I'm thinking it also blocks the grass roots ability to get nutrients after prolonged exposure. Just a guess though- could be something simple like chlorine burn.
 
DE is also used to kill bugs in the garden though Ive never used it. Maybe do some research there. Surely cant be the chlorine or everyone would probably see some dead grass unless it had way too much in it. Ive never killed or yellowed my grass.
 
It's interesting you didn't notice this the first year and only towards the end of the second year. Did you add borates to the pool or did you use Borax extensively? Did you add anything other than bleach and acid? Any algaecide or other products (probably not, but I'm asking just in case)?

It might just be the higher FC level you are keeping with a higher CYA level. Though the active chlorine level is low, the FC is what is relevant for grass since it is the chlorine capacity or reserve so the total amount that will react with a given area getting watered. It's higher than usually found in tap water that is often 1 or 2 and is limited to no more than 4 by the EPA. Some grasses tolerate chlorine better than others.

The other possibility is the salt level since that will build up over time unless you have significant water dilution (say, over the winter). You might test your salt level to see.
 
It can't be salt or borax. I have never used either in my pool. To be clear about the timing, this symptom (dying grass) was very apparent by the beginning of the 2nd BBB season. I'm not looking at dead grass in this location. I am looking at bare dirt. I should post a picture. Thanks for all the responses.
 
My backwash has been going to the same spot for 9 years. All I can detect is the trees and grass seem to flourish.

The only things I have put in my pool is LQ, some cal-hypo one season, some pucks last season, muriatic and CYA.
 
dsm said:
It can't be salt or borax. I have never used either in my pool. To be clear about the timing, this symptom (dying grass) was very apparent by the beginning of the 2nd BBB season. I'm not looking at dead grass in this location. I am looking at bare dirt. I should post a picture. Thanks for all the responses.
Click to expand...
Bleach/chlorine adds some salt to the pool.....you'd have to test it to see what your PPM are.
 

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Not much though Harvey, and I don't think enough at all to kill grass.

What kind of grass do you have? My Augustine and Bermuda here thrive on my backwash, and it's one reason I don't want a salt pool later on. Sorry, I was thinking you had one. Honestly, I am stumped as to why this would happen. I have a buddy and he has his washing machine discharge out to the side on an Oak tree, and it flourishes along with the grass around it.
 
Salt even at SWG levels, will only kill grass in extremely arid areas, and then only after it has had quite some time to build up in the soil. Borates have the same issue, though they tend to wash out a little less easily, and so are also an issue in areas that are arid but not quite as arid as salt requires to be an issue.

DE is not a problem at all for grass (unless it is quite a thick layer), though it can be really bad for certain kinds of insects.
 
Please post a full set of water chemistry numbers and also list the specific products added to the pool including the brands. Maybe there is some additive in the specific bleach you are using. Be sure to include everything used both during the summer and over the winter including closing chemicals. Maybe something has metal ions in it or something else strange. Also, prior to BBB, how were you disinfecting your pool -- what products did you use?
 
FC - 2.5
pH - 7.8
TA - 110
CH - 375
CYA - 30

I use Chlorox for chlorination. I use Muriatic Acid from Lowes. They recently changed brand. Brand now is Kem-Tek. 31.5% Hydrogen Chloride. My assessment is that the current Muriatic Acid brand not is the culprit.

I live in TX. Pool is 'open' all year round, I have no closing/opening routines that I perform.

Prior to BBB I did the standard chlorine pucks, occasional shock, and acid to manage pH. When I started BBB I had to drain 3/4 (or more) of my pool to rid myself of ridiculously high CYA.

(edited to correct the statement about Muriatic Acid - NOT the culprit)
 
That's really strange. I don't see anything out of the ordinary. Even the FC isn't that high because your CYA isn't high. I don't know what would be in the Muriatic Acid (hydrochloric acid) since it's normally just diluted with water. Clorox has a small amount of sodium polyacrylate in it, but lots of people use that and have no problems with their lawns.

Having it open year round would tend to build up salt if there were no water dilution, but at 2 ppm FC per day that would be around 100 ppm salt increase per month. And grass usually tolerates salt reasonably well (depending on species). With bleach, you'd build up salt twice as fast as when using Trichlor though of course with Trichlor you build up CYA. You probably build up salt even more than twice as fast because your CYA is lower now so your chlorine usage might be higher (unless you were fighting algae blooms when you were using Trichlor).

You might get a salt test just to see. Does the water taste salty? In my own pool I found the salt level rising and decided to use winter rains to dilute the water each season. Even so, I'm usually not higher than 1500 ppm salt at the peak.
 
I am in PA ~ pool was put in last year I am doing additional landscaping this year. I have just this season seeded and strawed my backwash area and all is well ~ all is well but I am mindful of the sun & temps when I backwash.

I live across from a golf course. My grandparents kept 8 acres mowed, bagged and flawlessly landscaped, with wonderful flower beds, IG Pool that was backwashed when necessary. Golf course does their very early morning / late at night. My Grandparents directed their backwash down across the fence line so it didn't puddle in the manicured yard. They had more than green thumbs, they had green hands. Grass can burn/boil from being watered "Incorrectly" in extreme heat, just like plants in your garden or flower beds. It will also burn if scalped when mowing. Yes we ran sprinklers to play in and it wasn't instant death to the yard, but sprinklers ran considerably longer than backwash process, we never ran the sprinkler in the same place: spots were always picked for places that would not puddle. When that water puddles during the heat of the day you will boil your grass.

In Texas with the brutal heat, I would think you have to be even more careful than I do up here. Maybe something is reacting to your soil, that I don't know about, but if you are backwashing in the heat of the day and that water puddles you are most likely burning/boiling your grass. I would think your heated soil doesn't drain as well as ours so it's not the chemicals reacting and killing your grass, but it is being boiled to death in the backwash area. Backwash after the heat of the day, after the sun has gone done to avoid the boil, allowing the water to saturate the soil and I would bet you will see a better result.
 

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