I’ve been using the Red Sea phosphate pro yet kit for months with a constant reading of between 0.08 and 0.12 so I’ve alway thought my phosphate sits around 0.1 today I bought the Hanna phosphorus ulr checker and tests my water and it flashed 200 I did another test and got the same I then diluted the 10ml reading with 5ml tank water and 5ml rodi and it read 120 which would mean my phosphate is 0.735 if correct. I use the Hanna alk so vile is clean inserted in with the 10ml facing forward each time and have used a brand new syringe to put the water in the cuvette. After the 3 tests I used my Red Sea pro kit again and it read 0.08 any ideas what’s going on. Hanna ulr is brand new and the sachets are in date
I experienced something similar when I first purchased the hanna phosphorous ulr kit. Here are a couple of things I learned, I now have absolutely no problems getting accurate readings every time (it's the best and most important test kit I own tbh):
1.) The phosphorous ulr kit seems to be the most sensitive to not filling it precisely on the fill line. Always ensure you are filling it smack dab on the fill line everytime, that means the meniscus as well. The kit often gives crazy readings when you don't fill it appropriately. This is the first thing I'd check and fix.
2.) Be sure to remove ALL air bubbles, every time. When I use the kit, I initially fill the cuvet and then tap the top/bottom multiple times to get the immediate air bubbles out. I then tilt it on it's side and slowly roll it which tends to get rid of the larger bubbles. I perform this before I fill with reagent and after I shake (before inserting the cuvet into the kit for the final reading).
3.) Never handle the cuvet directly to ensure that you are never leaving fingerprints on the cuvet. Fingerprints will cause crazy readings. I use a paper towel every time I interact with the cuvet and also wipe to remove any potential fingerprints/other embeddings on the cuvet before and after use.
4.) Place the cuvet in the same position for both the C1 and C2 readings.
5.) Maintain the same process every time you use the test kit. Here is my exact procedure every time I test:
A.) Pre-cut the reagent and fold it, working the reagent to the bottom of the package for a very quick pour.
B.) Remove the cuvet with a paper towell, wiping the sides in the process.
C.) Fill the cuvet until the meniscus is smack dab on the fill line of cuvet, DO NOT rush through this.
D.) Remove all bubbles from the cuvet by both tapping the top/bottom and then rolling the cuvet.
E.) I use my phone to have a timer ready as soon as the test kit is done with c1. I do this to know exactly how long I need to shake for to not get past the 3 minute turnoff.
F.) I immediately pour the reagent that I pre-prepared which allows me to do this in under 5-10 seconds.
G.) I shake violently for 1 minute and then slowly for the remaining minute.
H.) Since I'm only at 2:30 seconds after shaking for two minutes, I use the time to tap the top/bottom again and roll to remove all air bubbles.
I.) Place the cuvet back in and get your final c2 reading.
J.) Be sure to quickly clean out the reagent in under 2 minutes after getting your ready to avoid staining the cuvet. I typically fill several times with tap water and then one last time with ro/di water. Also be sure to wipe off all the sides and the water from the cuvet once complete.
I do this exact procedure like clockwork every time I read phosphate and it's very accurate.
