Normal for po4 to shoot up after stirring sandbed?

2wheelsonly · 12/14/2017, 01:08 AM

I stir up my sand bed around once per week, this is due to my flow pattern over time creating larger sand piles and my diamond goby going nuts moving things around.

On a typical day I can't get a reading using color po4 test kits (nyos/salifert) and my hanna ULR checker reads 0.01-0.02.

After stirring all test kits read 0.08-1.0 and then after a few hours goes back down to 0.01ish.

Is this hurting anything? I notice no crazy effects on my corals; my nitrates are around 20 and I intentionally run a higher nutrient tank (no carbon or GFO, just skimming and 10% monthly wc).

Tripod1404 · 12/14/2017, 01:16 AM

Does it read higher with URL reader? That device is basically a very simple spectrometer, it would be influenced by the turbidity of the water. So string up sand might cause false PO4 readings.

lapin · 12/14/2017, 05:00 AM

Quote:

Originally Posted by 2wheelsonly

I stir up my sand bed around once per week, this is due to my flow pattern over time creating larger sand piles and my diamond goby going nuts moving things around.
Is this hurting anything? I notice no crazy effects on my corals; my nitrates are around 20 and I intentionally run a higher nutrient tank (no carbon or GFO, just skimming and 10% monthly wc).

Key phrase "I notice no crazy effects on my corals". I think that stirring up the sand bed on a regular basis is a good thing. This keeps it cleaner in the long run, and keeps toxic substances from developing. Much better than doing it once a year, which can be a problem.

Vinny Kreyling · 12/14/2017, 10:28 AM

If you sample tank water for phosphate & water from siphoned sand bed after it clears you should notice quite a difference.

ca1ore · 12/14/2017, 05:36 PM

Wouldn't say it's normal, though not necessarily unexpected. Thing that strikes me as a bit odd is that the elevated level goes back down quite quickly. I don't test for phosphate, and don't stir my sand .... Perhaps for folks that do it is normal.

Dan_P · 12/14/2017, 06:21 PM

One explanation is that the spike in phosphate concentration is from a fine solid that becomes suspended when the substrate is stirred which subsequently resettles or is removed by filtration or skimming. The test for phosphate involves acid which could dissolve the solid, making soluble phosphate.

2wheelsonly · 12/15/2017, 01:21 AM

Sorry I had a typo in the original post I just caught, it spikes to 0.1 not 1.0 ... big difference but still same concept.

I tested water from siphoning sand bed against regular tank water before sifting and there was a difference just like Vinny mentioned. Tank water 0.01 sand bed 0.08. I am constantly stirring my bed and my sand looks like it’s brand new on an almost 3 year setup. Not sure if I should let it go but nothing has died yet so I guess if it ain’t broke don’t fix it! I don’t think I could let it sit if I tried as my vortechs, gyre and mover causes mini sand tornados now and then...

Rover88 · 12/15/2017, 06:41 AM

Quote:

Originally Posted by Tripod1404

Does it read higher with URL reader? That device is basically a very simple spectrometer, it would be influenced by the turbidity of the water. So string up sand might cause false PO4 readings.

This is the answer.

When you add the powder, what that does is binds to the phosphate and makes it 'visible', if only lightly. A colorimeter works by measuring absorption of a specific wavelength of light.

Having stirred up the water, you've created silt and debris in the water that probably clouds the water, right? Even a little bit will skew the colorimeter. Much the same way that the manual says to keep the glass clean and avoid scuffing it, these things block the light.

12/14/2017, 01:08 AM	#1
2wheelsonly Registered Member Join Date: Apr 2016 Location: Floyds Knobs, IN Posts: 259	Normal for po4 to shoot up after stirring sandbed? I stir up my sand bed around once per week, this is due to my flow pattern over time creating larger sand piles and my diamond goby going nuts moving things around. On a typical day I can't get a reading using color po4 test kits (nyos/salifert) and my hanna ULR checker reads 0.01-0.02. After stirring all test kits read 0.08-1.0 and then after a few hours goes back down to 0.01ish. Is this hurting anything? I notice no crazy effects on my corals; my nitrates are around 20 and I intentionally run a higher nutrient tank (no carbon or GFO, just skimming and 10% monthly wc).

12/14/2017, 10:28 AM	#4
Vinny Kreyling Registered Member Join Date: Nov 2002 Location: Miller Place, NY Posts: 7,206	If you sample tank water for phosphate & water from siphoned sand bed after it clears you should notice quite a difference. __________________ 250 gallon mixed reef, 2 Reefbreeder's Photon V 2, Deepwater BLDC 12, DAS EX-3 Skimmer, MTC mini cal, 2-3/4" Sea Swirls, Aquacontroller & 6 Tunze pumps.

12/14/2017, 05:36 PM	#5
ca1ore Grizzled & Cynical Join Date: Apr 2006 Location: Stamford, CT Posts: 17,319	Wouldn't say it's normal, though not necessarily unexpected. Thing that strikes me as a bit odd is that the elevated level goes back down quite quickly. I don't test for phosphate, and don't stir my sand .... Perhaps for folks that do it is normal. __________________ Simon Got back into the hobby ..... planned to keep it simple ..... yeah, right ..... clearly I need a new plan! Pet peeve: anemones host clowns; clowns do not host anemones! Current Tank Info: 450 Reef; 120 refugium; 60 Frag Tank, 30 Introduction tank; multiple QTs

12/14/2017, 01:16 AM	#2
Tripod1404 Registered Member Join Date: Mar 2016 Posts: 1,821	Does it read higher with URL reader? That device is basically a very simple spectrometer, it would be influenced by the turbidity of the water. So string up sand might cause false PO4 readings.

12/14/2017, 06:21 PM	#6
Dan_P Registered Member Join Date: Aug 2014 Posts: 1,432	One explanation is that the spike in phosphate concentration is from a fine solid that becomes suspended when the substrate is stirred which subsequently resettles or is removed by filtration or skimming. The test for phosphate involves acid which could dissolve the solid, making soluble phosphate.

12/15/2017, 01:21 AM	#7
2wheelsonly Registered Member Join Date: Apr 2016 Location: Floyds Knobs, IN Posts: 259	Sorry I had a typo in the original post I just caught, it spikes to 0.1 not 1.0 ... big difference but still same concept. I tested water from siphoning sand bed against regular tank water before sifting and there was a difference just like Vinny mentioned. Tank water 0.01 sand bed 0.08. I am constantly stirring my bed and my sand looks like it’s brand new on an almost 3 year setup. Not sure if I should let it go but nothing has died yet so I guess if it ain’t broke don’t fix it! I don’t think I could let it sit if I tried as my vortechs, gyre and mover causes mini sand tornados now and then...