DPD powder R-0870

Illupo

Active member
Jul 3, 2016
38
Scottsdale
#1
Just opened my replacement jar of DPD powder and it is stupid question time again. The jar I just ran out of came with my TF100 kit a year ago February. The powder was ash gray. The new one is as white as the snow. Huh? Hard to believe the same chemical is two different colors. Have not tried the new one to see if it works any differently, but was wondering if there is (or was) something wrong with one of the powders? If I need to get a replacement, now is the time.
 

JoyfulNoise

TFP Expert
Platinum Supporter
May 23, 2015
14,509
Tucson, AZ
#2
Normally the DPD powder is white. As it ages and is exposed to heat and humidity, it can take on a grayish color. It does not affect the readings. If the powder gets purplish-black, that is an indication of extreme moisture exposure and the powder is likely no longer good.

The test kit chemicals really need to be stored indoors in a cool and dry space. They should only be taken out for testing and then returned indoors. Heat and humidity exposure can easily degrade them.
 

Illupo

Active member
Jul 3, 2016
38
Scottsdale
#3
That is interesting! I have always kept my kit inside a cool, dark closet in the house. The gray one that came with the kit then a year ago must have been somehow exposed.
 

JoyfulNoise

TFP Expert
Platinum Supporter
May 23, 2015
14,509
Tucson, AZ
#4
That is interesting! I have always kept my kit inside a cool, dark closet in the house. The gray one that came with the kit then a year ago must have been somehow exposed.
It can happen during shipping. Since you're up in Scottsdale, I would suggest you only order reagents in the early Spring or late fall when the temperatures are cool. A box with test chemicals in them sitting out in a hot mailbox can easily go bad.
 

Eilum

Well-known member
Jun 19, 2016
102
Jackson NJ
#5
I just got a new one as well. The old one was purple/black but I have been using it to test. Should I assume that the readings were not accurate? Seemed to clear the pool at those levels!
 

smankins

Bronze Supporter
Feb 10, 2017
98
Longview / Texas
#6
I am a new pool owner and ordered my TF-100 kit not long ago and have been using it since pool was installed late March. My powder came in grey - thought it was normal. I keep the test kit in the house in a closet. The powder has never gone outside since I got it. I also have a small bag of silica gel in there with it.
 

JoyfulNoise

TFP Expert
Platinum Supporter
May 23, 2015
14,509
Tucson, AZ
#7
I just got a new one as well. The old one was purple/black but I have been using it to test. Should I assume that the readings were not accurate? Seemed to clear the pool at those levels!
I am a new pool owner and ordered my TF-100 kit not long ago and have been using it since pool was installed late March. My powder came in grey - thought it was normal. I keep the test kit in the house in a closet. The powder has never gone outside since I got it. I also have a small bag of silica gel in there with it.
White or grey is fine. Even when it starts to turn black, it will still work. The problem with humidity is that it makes the powder clump together and form hardened and caked up chunks. As long as you keep it indoors and out of the heat and humidity, it will be fine. The Taylor R-0870 DPD powder bottle actually has a desiccant built into the wall of the bottle. It's a very special type of packaging for moisture sensitive powders but it also means that the cost of that bottle is more expensive than other sources. Even with that built in desiccant, I have received R-0870 containers where the powder was a little off-white/grey.

It will work for you so I would just continue with what your are doing.