food, nutrient test

Wiz · Mar 30, 2016

Hey guys,
My nitrates are up to 40ppm and phos is up to .25. My fuge usually keeps these at 0 but I recently cleaned out a lot of macros and redesigned it. Also started feeding reef chilli every other night to help my suffering acans. So it got me thinking about how much waste comes from each type of food.
I'm thinking friday I will set up a small number of containers with my tank water in them. Put a small amount of each food in its own container and let them sit for two days then run my nitrate and phos tests. One will be just water.
Do you think the test will work with only my water in each. (No lr or sand) or will there not be enough bacteria to tell?
Any suggestions on how I might improve the test? I'd love to rank my foods by dirtyness.
My foods are
Live brine adults
Live brine babys
Live blackworms
Flakes
Pellets
Frozen mysis
Homemade Frozen seafood mix
Reef chilli

donnievaz · Mar 30, 2016

I'm no scientist but I think you'd be better off leaving the food for a few hours then straining it out before you test. Leaving it in for two days is going to just make a stinky mess. Just make sure you leave all the samples in for the same amount of time and that should give you a decent baseline to test from.

Wiz · Mar 30, 2016

So you think a couple of hours will have an effect on the water? I thought at least a day

donnievaz · Mar 30, 2016

Wiz said:
So you think a couple of hours will have an effect on the water? I thought at least a day

Definitely.

Wilsoni · Mar 30, 2016

This is an interesting article and I would be curious to see the results. Based off your list, my guess is that reef chilli along with any other fine particle food would have the most profound effect.

Wiz · Mar 30, 2016

I will do my best to make sure that it is fair and the results are accurate.You think putting the small amount of each food in a paper towel and sinking it in the cup would do the same. So that it's easier to remove

Rybren · Mar 30, 2016

I think that Randy has run some of these types of tests and has an article on the results. I can't seem to find it now. Will keep looking.

Edit: This isn't the newer article that I was thinking of, but it has a couple of tables that show the amount of P in various types of foods...

http://www.advancedaquarist.com/2012/3/chemistry

Randy Holmes-Farley · Mar 30, 2016

IMO, this type of test isn't very useful because it only detects nitrate and phosphate that comes off the foods, and doesn't account for the vast majority of N and P sources in the foods that are still present as organic molecules. There shouldn't be much nitrate, and the phosphate will be only a tiny fraction of the total.

Here's my analysis of phosphate in foods using other peoples measurements of total P in foods:

Aquarium Chemistry: Phosphate And Math: Yes You Need To Understand Both
http://www.advancedaquarist.com/2012/3/chemistry

here's the conclusion from it on rinsing, which relates to this sort of test:

Rinsing Foods and the Effect on Phosphate
Now that we have some information on the phosphate in foods, we can critically examine the concern that many aquarists have about foods, and specifically their rinsing of frozen foods before use. A typical test you see is someone taking a cube of fish food, thawing it, and putting it into a half cup of water. They then test that water for phosphate and find it "off the charts". Let's assume that means 1 ppm phosphate, which would give a very dark blue color in many phosphate tests. Bear in mind this is a thought problem, not an actual measured value, but it is typical of what people think the answer is.

Is that a lot of phosphate? Well, there are two ways to think of the answer.

The first way is as a portion of the total phosphate in that food. A half cup of water at 1 ppm (1 mg/L) phosphate contains a total of 0.12 mg of phosphate. A cube of Formula 2 contains about 11.2 mg of phosphate. So the hypothetical rinsing step has removed about 1 percent of the phosphate in that food. Not really worthwhile, in my opinion, but that decision is one every aquarist can make for themselves.

The second way to look at this rinsing is with respect to how much it reduces the boost to the aquarium phosphate concentration. Using the same calculation as above of 0.12 mg of phosphate, and adding that to 100 gallons total water volume, we find that phosphate that was rinsed away would have boosted the "in tank" phosphate concentration by 0.12 mg/379 L = 0.0003 ppm. That amount washed away does not seem significant with respect to the "in tank" target level of about 50-100 times that level (say, 0.015 to 0.03 ppm), nor does it seem significant relative to the total amount of phosphate actually added each day in foods (which is perhaps 50-1000 times as much, based on input rates from Table 4. Again, the conclusion I make is that rinsing is not really worthwhile, in my opinion.