Why do I show elevated phosphates right after a water change?

optimisticdingo

Active Member
Review score
+0 /0 /-0
View Badges
Joined
Jan 13, 2021
Messages
140
Reaction score
59
Review score
+0 /0 /-0
Location
Norman, Oklahoma
So I've noticed that if I test phosphate directly after a water change I read elevated levels. If I check the next day the levels are more normal to what my tank has been reading.

I'm using the Hanna Phosphate checker, the standard one not the ULR.

In my 116 gallon my Phosphate was at .6ppm, after a 30% water change I checked and Phosphate was over 2ppm. I checked the next morning and it was down to .22. I'm not using a refugium or GFO so it seems that the levels elevate right after a water change. Any idea what causes this?
 
Top Shelf Aquatics

vetteguy53081

Well known Member and monster tank lover
Review score
+0 /0 /-0
View Badges
Joined
Aug 11, 2013
Messages
49,510
Reaction score
112,046
Review score
+0 /0 /-0
Location
Wisconsin - Florida in several months
Worst time to test is right after a water change when the tank is agitated from activity. Wait 12 hrs and reattempt test
 

GoVols

Cobb / Webb - 1989
Review score
+0 /0 /-0
View Badges
Joined
Nov 29, 2016
Messages
12,376
Reaction score
36,326
Review score
+0 /0 /-0
Location
In-The-Boro, TN
Reef Chasers Aquaculture

LisaAP

Active Member
Review score
+0 /0 /-0
View Badges
Joined
Apr 14, 2019
Messages
100
Reaction score
182
Review score
+0 /0 /-0
Location
UK
I found the same, Tropic Marin Pro Reef is not phosphate free. I found as much as 0.1ppm on freshly mixed TMPR using the Hanna ULR tester. However that wouldn’t account for the difference you are currently seeing after a water change.
 
OP
O

optimisticdingo

Active Member
Review score
+0 /0 /-0
View Badges
Joined
Jan 13, 2021
Messages
140
Reaction score
59
Review score
+0 /0 /-0
Location
Norman, Oklahoma
I found the same, Tropic Marin Pro Reef is not phosphate free. I found as much as 0.1ppm on freshly mixed TMPR using the Hanna ULR tester. However that wouldn’t account for the difference you are current seeing after a water change.
It's probably just due to the water being disturbed and it throwing the readings off
 
OP
O

optimisticdingo

Active Member
Review score
+0 /0 /-0
View Badges
Joined
Jan 13, 2021
Messages
140
Reaction score
59
Review score
+0 /0 /-0
Location
Norman, Oklahoma
I'd check the water change water (raw tap water could do it, but not 0 ppm TDS RO/DI).

Otherwise, I'm suspicious that the result is test error.
The water is 0ppm TDS RO/DI. I'm using the four stage BRS 150GPD system.

However, I've heard that plastics can release Phosphates and I store the water in plastic containers. Could this be the issue?
 
Lazy's Coral House

Randy Holmes-Farley

Reef Chemist
Review score
+0 /0 /-0
View Badges
Joined
Sep 5, 2014
Messages
45,700
Reaction score
34,904
Review score
+0 /0 /-0
Location
Arlington, Massachusetts, United States
The water is 0ppm TDS RO/DI. I'm using the four stage BRS 150GPD system.

However, I've heard that plastics can release Phosphates and I store the water in plastic containers. Could this be the issue?

Possible, but not super likely, IMO.

Anyway, test the new water to see.
 
Top Shelf Aquatics
Top