Anyone experience a phosphate spike after scraping back glass?

[Miami Reef]

In my experience, scraping the algae from the back glass will cause a noticeable spike in phosphates when I test it the following morning.

Does anyone else experience something similar with their tanks? Nitrates never seemed to have a change.

 

[killer2001]

If I look at my tank the wrong way phosphates spike up.

 

[A_Blind_Reefer]

In my experience, scraping the algae from the back glass will cause a noticeable spike in phosphates when I test it the following morning.

Does anyone else experience something similar with their tanks? Nitrates never seemed to have a change.

I’ve never checked myself. I’m wondering if there was more freeborn algae in the test sample….even overnight, that may have skewed the result

 

[LRT]

Interesting I've never checked it I'm curious what the pros have to say.
I have completely stripped my system of phosphates scrubbing and cleaning my rock.

 

[Dan_P]

In my experience, scraping the algae from the back glass will cause a noticeable spike in phosphates when I test it the following morning.

Does anyone else experience something similar with their tanks? Nitrates never seemed to have a change.

What are the before and after numbers?

 

[Double monti 61]

I usually scrape the glass during a water change to help remove some of the algae scraped off.

 

[Townes_Van_Camp]

If you scrape, and don't remove them, yes, you will get an increase in phos as the algae, film GHA, whatever decays it will release whatever nutrients they held. You may also experience a reduction in phos uptake which, would cause an increase in phos.

 

[Miami Reef]

What are the before and after numbers?

Around 0.05ppm to 0.20ppm.

This happened so many times that I even used to add a few TBSP of GFO in advance, and I would still get a rise!

 

[Dan_P]

Around 0.05ppm to 0.20ppm.

This happened so many times that I even used to add a few TBSP of GFO in advance, and I would still get a rise!

I wonder whether filtering the test sample with a 0.45 micron filter would get rid of the increase in the test result?

 

[Miami Reef]

I wonder whether filtering the test sample with a 0.45 micron filter would get rid of the increase in the test result?

I’ll do that. I’ll update with what I find.

 

[A_Blind_Reefer]

I wonder whether filtering the test sample with a 0.45 micron filter would get rid of the increase in the test result?

Or wait a full twenty four before testing to see if the tanks filtration eventually gets it.

 

[Miami Reef]

I wonder whether filtering the test sample with a 0.45 micron filter would get rid of the increase in the test result?

I have .22um filter, which should be even better.

 

[Dan_P]

I have .22um filter, which should be even better.

It would be good to test the water before and after filtering just to confirm the high phosphate effect. I suspect you were going to do that but just in case

 

[Miami Reef]

It would be good to test the water before and after filtering just to confirm the high phosphate effect. I suspect you were going to do that but just in case

Yep. I was going to. I know the basic rules. I’m going to rinse the vials 3 times with the filtered water prior to the fill for the filtered trial. For the regular trial, I will rinse with unfiltered tank water 3 times etc.

I will test 3 times each trial if the phosphates in the unfiltered water show a significant raise.

As a background, my tank tested 0.02ppm 3 times this week in a row with the hanna ULR PO4 checker. I’m confident that my current PO4 prior to scraping is 0.02ppm.

I will lay out everything organized tomorrow morning once I actually am able to test

Ps, I have 100 micron filter socks and a skimmer that is left in the tank running as normal. It will catch the loose algae. I’m not sure if I should change the socks and clean the skimmer now, or if I should not touch anything before my trials.

 

[Dan_P]

Ps, I have 100 micron filter socks and a skimmer that is left in the tank running as normal. It will catch the loose algae. I’m not sure if I should change the socks and clean the skimmer now, or if I should not touch anything before my trials.

Do what you normally do when you scrape algae and observe the phosphate spike.

 

[gbroadbridge]

In my experience, scraping the algae from the back glass will cause a noticeable spike in phosphates when I test it the following morning.

Does anyone else experience something similar with their tanks? Nitrates never seemed to have a change.

Yes.

To qualify that, if there is a significant buildup of green algae on the glass, I see a phosphate spike the day after I remove it. It's mechanically removed so I believe that the algae was consuming the phosphate for growth and once it has gone other organisms take time to catch up.

If I keep the glass clean, phosphates are normally stable day to day (around 0.05ppm).

edit: I run a roller mat with 17 micron filtration which is why I believe it to be mechanically removed very quickly. I doubt it has time to decay - in any event the algae would still consume phosphate even in the water column.

 

[Miami Reef]

Do what you normally do when you scrape algae and observe the phosphate spike.

Alright. I normally leave all the filters in place overnight. My thinking is that as the filters clog, they will filter more and more, which seems desirable to me. That’s what I have been doing, so I will replicate it tomorrow.

 

[A_Blind_Reefer]

Yes.

To qualify that, if there is a significant buildup of green algae on the glass, I see a phosphate spike the day after I remove it. It's mechanically removed so I believe that the algae was consuming the phosphate for growth and once it has gone other organisms take time to catch up.

If I keep the glass clean, phosphates are normally stable day to day (around 0.05ppm).

edit: I run a roller mat with 17 micron filtration which is why I believe it to be mechanically removed very quickly. I doubt it has time to decay - in any event the algae would still consume phosphate even in the water column.

I was wondering if maybe additional algae in a colorimetric device sample like a Hanna checker or the reagent having an effect with more algae particles in the water sample might have any effect. I would also be curious what a sample from the display would read when compared to the sump, post filtration. I know that it takes quite some time for particles to make their way up to the weir and through the filtration even with high flow powerheads. Just curious is all, I have zero scientific background at all.

 

[gbroadbridge]

I was wondering if maybe additional algae in a colorimetric device sample like a Hanna checker or the reagent having an effect with more algae particles in the water sample might have any effect. I would also be curious what a sample from the display would read when compared to the sump, post filtration. I know that it takes quite some time for particles to make their way up to the weir and through the filtration even with high flow powerheads. Just curious is all, I have zero scientific background at all.

Good points.

I always take water samples from the sump post filtration in order to mitigate any effect of particulates in the sample - which also means post GFO reactor.

 

[Dan_P]

I was wondering if maybe additional algae in a colorimetric device sample like a Hanna checker or the reagent having an effect with more algae particles in the water sample might have any effect. I would also be curious what a sample from the display would read when compared to the sump, post filtration. I know that it takes quite some time for particles to make their way up to the weir and through the filtration even with high flow powerheads. Just curious is all, I have zero scientific background at all.

That is the point of filtering the water taken from tha aquarium after scraping. If the algae residue is causing sample cloudiness (higher phosphate reading) or reacting with the reagent, filtering eliminates both effects. If the high phosphate reading remains after filtering, the effect is caused by something which is dissolved. e.g., phosphate.