Reading Salifert PO4 Test

[MrObscura]

Anyone use this? And if so do you have a hell of a time reading the lower end of the chart? I can't really tell the difference between 0.03 and 0.1 unless I put the vial half on the color and half on the white part of chart. 

 

This may be a stupid question but does that effect the reading since the instructions say to place it on the white part looking down? 

[Oldsalt01]

I had the very same issue, so I finally bit the bullet and ordered a Hanna ULR Phosphorus Checker. A litle bit complicated, because of the timing involved, but I’m super happy with it, and there’s no ambuguity involved. The secret is to have the chemical packet open before you start the zeroing timer.

[MrObscura]

Yea, I don't really want to spend 50 bucks on a po4 test. I'm happy as long as po4 is not 0 and not well above 0.1.

[SeaFurn]

50 minutes ago, MrObscura said:

Anyone use this? And if so do you have a hell of a time reading the lower end of the chart? I can't really tell the difference between 0.03 and 0.1 unless I put the vial half on the color and half on the white part of chart. 

 

This may be a stupid question but does that effect the reading since the instructions say to place it on the white part looking down? 

I have a hard time with that as well. I slide the sample back and forth back and forth trying to figure out which one to go with.

 

The color is so faint at the lower end that I doubt placing half the sample over it has much effect on your reading. 

[MrObscura]

Without doing the half and half approach it looks like anything clearly above 0 to something clearly below 0.25. With doing half and half it's clearly blue but not as dark as 0.03. If that's my actually reading, great. But, hell if I know lol 

[Clown79]

I stopped testing phos because the kit read 0 all the time unless I pulled water from the sandbed...I couldn't tell what my results were then.

 

I just ordered the Hanna ULR

[seabass]

With the Salifert test kit, if you can't see any trace of blue, then phosphate is probably too low.  You want the very slightest tinge of blue.  If you can't tell if the results read either 0.03 or 0.1, then phosphate is usually too high.

 

I wish the resolution was better, but it is usable.

[Beer]

I agree with Seabass. Closer to 0.1 might be less ideal, but doesn’t really require immediate action. Maybe assess what you are feeding and how often as some foods will add more phosphates than others. Maybe do a slightly larger water change or add an etra one half way through your normal cycle.

 

I’m actually thinking of doubling the testing amount to see if it makes it easier, though it may make the sample appear darker. I’ll probably make a standard and run the sample with 1ml and 2ml at different levels to see how it works out. The lights I use for colorimetric tests have really good color rendition, but causes too much shadowing with the 1ml sample to really judge the low range colors. There is a lot of sliding back and fourth and turning slightly to minimize shadows. Next test I might try pouring the sample into other vials from old test kits to see if there are others that allow for easier reading without shifting the percieved color.

 

The exact number isn’t critical. I need to do a little more research, but I came across some numbers showing an ideal phosphate to nitrate ratio of 160:1 based on assimilation ratios in some deeper water algae species. That would put something around .03 ppm PO4 to 5ppm NO3 at a good ratio. As long as it looks closer to .03ppm than adjacent levels, it is good. If you aren’t suddenly having issues from elevated PO4, which I’d imagine you would have less trouble differentiating colors from those levels, the exact reading isn’t critical. It took me a little bit to accept this as I prefer to be a bit more precice with things. We aren’t performing chemestry experiments or developing medications, exact levels aren’t critical and knee-jerk reactions to slight changes leads to more harm than good (insert “nothing good happens fast” mantra here). People are starting to shift away from the ultra low nutrient mentality of no phosphate or nitrate is ideal and realizing that lower levels are actually better for photosynthetic organisms and their symbionts (most coral in the hobby).

[MrObscura]

The only reason I'm bothering with po4 really is because I dirtied up my tank to combat dinos and po4 got really high as a result, so now I'm just trying to get it below 0.1 and find a balance to keep it there. 

[Beer]

Working on the same. I had old test kits that made me think my phosphates were off the chart and nitrates 0.

 

I’m dosing to kep phosphate on the high side of 0.03. Things are looking much better for me.

[Beer]

If you don’t want to go with a Hannah chacker, look into the Nyos kits. I’ve been pretty happy with the calcium and magnesium. Pretty simple and straight forward titrations. Simpler and faster than what I’ve seen on other kits.

 

I forgot I got the Nyos nitrate and phosphate kits when I bought the Salifert kits. The Nyos phosphate range is from 0.025 to 1.0 with a total of nine steps. 0.025-0.075 looks like it might be hard to decipher, but the vials go into a foam block before being placed over the color chart (one for sample, one for referencing colors), so it may not be as difficult to determine as it initially appears. It basically functions like the Red Sea Pro kits with the color wheel. The color change is blue, which might be better if you are red/green color blind. The blue at 1.0 is quite pronounced.

 

I’ll run the test on Salifert and Nyos side by side when I test tomorrow to see what the difference is. The results are not as fast with the Nyos kit (10 min for phosphate), but if you are concerned about actual levels below 0.25ppm, it might be the way to go. If you test phosphate very infrequently and levels are elevated above 1.0, you may need an alternate method to see how high they actually are to determine what your immediate actions, if any, should be. Whether that is the Salifert as backup or running a sample to the LFS, is up to you. I don’t really think keeping a second kit for higher range would be critical as elevated phosphate likely wouldn’t be harming anything for the extra day you might have to wait before attaining results.

[MrObscura]

Yea, I'm not particularly concerned with po4. Only reason I am right now is because I really dirtied up the tank to get rid of dinos and po4 got up there. 

 

I just want them between 0.01 - 0.1. saliferts just so damn hard to read. But after running chemipure blue now for a few say po4 has cleary dropped below 0.1 so I've pulled the chemipure and I'm now just going to let the tank do its thing and see if it stays put. 

[Beer]

I just finished testing phosphate. I haven’t dosed phosphate in a couple of days and intentionally didn’t dose today.

 

With the Nyos kit, I am sitting just under 0.025ppm, the lowest non-zero reading on the card. It clearly wasn’t zero and took minimal sliding back and forth to determine that it wasn’t the next level up and wasn’t quite 0.025.

 

With the Salifert kit, I couldn’t really tell if it was zero or 0.03. It didn’t appear to be 0.1, but I was struggling to determine the level. I was pretty certain it wasn’t zero due to previous experience with the kit (checked Salifert before Nyos), but it took rinsing the sample container and adding 4ml of clean water to verify that there was actually detectable levels.

 

 

I know you aren’t really concerned at this point, but if you are looking for another kit in the future, I’d look to Nyos if you don’t want to go with a digital solution. As long as your levels are typically below 0.1ppm, it is a good kit. The shop owner mentioned that other people were upset with the kit because it is ultra low range and people that are typically looking to monitor phosphate have higher levels, so it is useless to them.

 

 

Interestingly, my nitrate was reading about 160 times higher than the phosphate three days ago and it has maintained that ratio (as far as is discernable with the precision of the kits). Nitrate to phosphate went from about 5ppm:0.03ppm to just over 2ppm:just under 0.025ppm. Anecdotally, it does appear that the uptake levels are around 160:1.