Phyto Feast/Oyster Feast adding Phosphate?

[JohnV8r]

Four days ago I had zero phosphates in my tank. Today I have .5 phosphates per an API test. Tested my RO water and the phosphates are zero. The only other thing that has been added to my tank is 1 tsp of Phyto Feast and 1 tsp of Oyster Feast.

Is it possible that Reef Nutrition Phyto Feast and/or Oyster Feast contain phosphates?

[bertoni]

Any food will contain some phosphorus, which can be converted to phosphate via decay. I'm not sure that I trust the kit, though. That's a big change. How big is the tank?

[JohnV8r]

The system is an estimated 194 gallons with sump, refugium, live rock, sand, etc. Display tank is 175 (48L x 28D x 30T). Phosphate is my only non Elos test kit. However, I tested the tank and then the RO water (and I swear this time I used the right amount of water this time) and the RO water had zero phosphates.

I hope you're right that it's a test kit error.

[bertoni]

Well, if the kit is correct, the phosphate came from somewhere. I'm still suspicious, though, since that's a lot of phosphate. It'd be from the Oyster Feast, most likely, of the two food items mentioned.

[JohnV8r]

What would be a fair solution to test the Oyster Feast (OF) for phosphates? One drop of OF in a 5 or 10 ml solution of RO water? I can test the RO water first and then test a solution with the OF. I just need to know what a fair representation of OF in RO or salt water would be.

My phosphate test is an API. I'm not under some illusion that it's the most accurate test available. However, it's the fact that my tank and my RO water were at zero two testing periods in a row (four days) and there was a jump to .5 AFTER I fed the Phyto and Oyster Feast.

If there is another source, I would like to figure out what it is. I'm vodka dosing .7 ml of Absolut Vodka daily and I feed spirulina enriched brine shrimp (one half cube twice daily) with a tiny pinch of Omega One Super Veggie Kelp Flakes (once daily) to prevent lateral line disease in my tangs. I use Seachem's Reef Salt for water changes.

Let me know what you think is a fair amount of OF to test.

Thanks

[soverjas]

Let me know what you think is a fair amount of OF to test.

Thanks

I would try to mimic the scale the best you can that you added to your tank which wouldn't be much. Maybe try like 1ml to a half a cup of water. I would use salt water as your salt could have phosphates as well to make it a fair test. maybe test your salt water before adding the Oyster Fiest.

[disc1]

Also be aware of the fact that not all (actually most) of the phosphate in the food is not inorganic phosphate. It's bound into molecules like phospholipids and proteins. So the test on the food itself may give deceptive results compared to putting the food into the tank and letting nature chew on it for a while.

[JohnV8r]

@disc1: Interesting that you said that. I was wondering the same thing.

I actually calculated my 194 net gallons to be 148,992 teaspoons of saltwater. I added 1 tsp of Phyto Feast and 1 tsp of Oyster Feast when I had the phosphate increase. That represents .001342353% of the volume of my system. Intuitively, it seems unlikely to me that adding that small amount in and of itself could create .5 phosphate.

However, when you take into account how smelly my system gets when I put 1 tsp each of Phyto & Oyster Feast and turn the skimmer off for an hour, you start to realize that if this is the source of phosphate it likely is the result of, as you said, "letting nature chew on it for a while." My system doesn't smell immediately after adding Phyto & Oyster Feast. It smells after an hour of circulating it without the skimmer on.

I could be chasing my tail on this whole thing. I used some phosphate absorber to take the phosphate back out of my tank. I think the most indicative thing I could do at this point is verify a reading of zero, feed the Phyto & Oyster Feast at night, and see what the phosphate reading is the next morning.

We'll see what happens.

[bertoni]

That sounds like a good experiment.

[JohnV8r]

I'm going to have to wait for three things before I do the test:

1. I have to get this trip out of the way next week, and

2. I need a new phosphate test kit. I just ran Kent Phosphate Sponge in a canister filter for 1.5 days and I'm still showing .5 phosphate. I have not added any Phyto or Oyster Feast during the period I ran the cannister filter. The ONLY other possible stimulus I can recognize at this point is that my Diamond Goby is turning over my new (< 2 months old) sand bed and may be causing some materials (silicates?) that didn't come out in the rinse to be released. However Occam's Razor makes me think it's the test kit.

3. I've always had good results with ROWAphos. I hadn't used Kent Phosphate Sponge before this episode (it was all that was available at my LFS). I want to pick up some ROWAphos and run it in my Phosban reactor to ensure I start with phosphate at zero before the test. That way I can run a base line test by getting the phosphates to zero and shutting the Phosban reactor off for two days to see if I have any increase in phosphates without the Oyster Feast and Phyto Feast.

I definitely will run the test soon though. Oyster Feast, Phyto Feast, and the rest of the Reef Nutrition products have been a regular part of my reef keeping for the last few years. I want to know if they are causing me a phosphate problem.

Stay tuned.

[kgross]

You are also adding other foods to the tank you said which will will have P in it as well.

On your test kit, it could very easily be testing error as well, tank could have been around .2 or so, and showing up as zero, then next test was closer to .4, but looked more like .5, so it might not have been a .5 increase at one time.

[JohnV8r]

Those are both great points Kim. I think the reason why I was looking at the Phyto & Oyster Feast is because I had multiple tests over a period of time come back with 0 phosphates. Only after I added the P & OF did I get a higher test reading. The other food added was static throughout the whole span of testing.

I hope this turns out to just be test kit error.

[JohnV8r]

I've run the test now to see if I could replicate the phosphate spike. I could not get the phosphate to spike. In fact, the interrupted vodka dosing that I have done (dosed for one week, had to go out of town for a week, dosed when I returned) has dropped my nitrates and phosphate to zero. In fact, I can't get either to spike with the Phyto & Oyster Feast.

In looking back at this, I think it may have been either test kit error or some of the material in the deep sand bed that didn't wash out that was being released that caused the phosphate to increase.

[bertoni]

Okay, well, as long as the phosphate remains low, I think the problem's solved. :)

[Ron Reefman]

And now I can go back to feeding with Phyto & Oyster Feast. Whew. To be honest, I didn't think this was the issue. I feed with these products fairly regularly and my nitrate and phosphates are always zero.