Phosphate spike after waterchanges?

[Diveks]

I am not sure if this is a stupid question or not but ive have noticed my tank has crazy phosphate spikes after every change. maybe stirring the sand up too much or something? The new water always tests 0 phosphate (i am using hanna) but after the water change it can go up to 0.8-1 which concerns me. this will go down in around 2 days back to the 0.03-0.06 ranges. It stays pretty constant until the next water change.

Most do water changes to decrease phosphate but here I am spiking mine. Im concerned for the health of the corals as they are obviously not happy about the spike. Should i be worried or just let it ride out? anything I could do to make the levels more stable? Im not sure if this much of a spike during a water change is normal.

 

[ahiggins]

That’s really weird. Using RODI? Dirty pump? Process of elimination-pump, water source, container, wonky test (probably not this one if it’s repeatable).
do you stir up the sand, or pour it on rocks when you change it. Rinsing filter media accidentally. Kicked up sump detritus?

 

[Rickybobby]

after i stir the sand up, vaccum and do a water change i let the filter floss suck everything up, than i change it, are you cleaning your filtration??

 

[Diveks]

That’s really weird. Using RODI? Dirty pump? Process of elimination-pump, water source, container, wonky test (probably not this one if it’s repeatable).
do you stir up the sand, or pour it on rocks when you change it. Rinsing filter media accidentally. Kicked up sump detritus?

Yes RODI and its at 0, the container is always cleaner after use and when its still in the bucket its at 0 ppm phosphate. I siphon the sand every water change could the detritus cause such a big spike?

after i stir the sand up, vaccum and do a water change i let the filter floss suck everything up, than i change it, are you cleaning your filtration??

Yes i use a filter sock i clean out every 3 days (i always change it out a few hours after a water change too). The sump is spotless too as i suck all the detritus every few weeks. The numbers will go back down to normal levels but im not sure what is causing the giant spike a few hours after the water change.

 

[TheDragonsReef]

Unless you're vacuuming the sand, you shouldnt just stir it up. And you should only vacuum sand if you do it consistently, dont vacuum every few months. Otherwise just leave the sand alone.

 

[Duffer]

Most salt on the market has some degree of phosphates…it has been discuss many times on this forum…do a search…

Randy has also spoken about it

 

[vetteguy53081]

If your doing a phosphate test immediately after water change- you are likely getting a false reading. Wait 8-12 hours then test.

 

[jgirardnrg]

I had a similar situation... I was chasing high PO4 for months and couldn't nail down where it was coming from. Turns out that the TDS meter on my RODI unit was lying to me and the PO4 was coming from there. Swapped out all the filters and problem solved. Double check the RODI.

 

[Diveks]

Unless you're vacuuming the sand, you shouldnt just stir it up. And you should only vacuum sand if you do it consistently, dont vacuum every few months. Otherwise just leave the sand alone.

Yes i misspoke i never just stir up the sand. Every water change i vacuum the sand. Maybe too much detritus is in the sand?

Most salt on the market has some degree of phosphates…it has been discuss many times on this forum…do a search…

Randy has also spoken about it

Ah im using red sea blue bucket and i see there are some that find phosphate in theirs. Might be that and added phosphates from too much detritus i think.

If your doing a phosphate test immediately after water change- you are likely getting a false reading. Wait 8-12 hours then test.

Ohh i see, ill stop the immediate tests then and test the next day.

I had a similar situation... I was chasing high PO4 for months and couldn't nail down where it was coming from. Turns out that the TDS meter on my RODI unit was lying to me and the PO4 was coming from there. Swapped out all the filters and problem solved. Double check the RODI.

Just changed it out a week ago no difference, with 2 tds and 0 same PO4 spike (after it is in the tank though.

 

[jgirardnrg]

Ok... was just making sure. I chased my tail for a while trying to figure that out. I use the same salt and do not see elevated PO4 after water changes. In fact, I dose phosphates and nitrates to my frag tank or they'd bottom out on me.

 

[Lavey29]

I recently started deep siphon cleaning my sand and it spiked my phosphate also. They recommend only doing 25% of your sand per water change. I'm guessing this is to prevent spikes.

Water changes will lower nitrates but do not have much impact on phosphate.

 

[Diveks]

Ok... was just making sure. I chased my tail for a while trying to figure that out. I use the same salt and do not see elevated PO4 after water changes. In fact, I dose phosphates and nitrates to my frag tank or they'd bottom out on me.

Kinda wish i have the same problem here. My phosphate weirdly goes from high to low after water changes which is the opposite since most people use water changes to lower phosphate, mine increases it. I think that means my phosphate control in the tank works pretty well at least.

I recently started deep siphon cleaning my sand and it spiked my phosphate also. They recommend only doing 25% of your sand per water change. I'm guessing this is to prevent spikes.

Water changes will lower nitrates but do not have much impact on phosphate.

Oh i see, might just have to siphon less, maybe mostly just the part which holds most detritus.

 

[Icryhard]

If your doing a phosphate test immediately after water change- you are likely getting a false reading. Wait 8-12 hours then test.

how can a water change cause a false reading? I changed about 2 l of water (no stirring or whatever) and it went from 0.11 to 0.18
I’ll check again today to see if this has gone back to 0.11

 

[Dan_P]

I am not sure if this is a stupid question or not but ive have noticed my tank has crazy phosphate spikes after every change. maybe stirring the sand up too much or something? The new water always tests 0 phosphate (i am using hanna) but after the water change it can go up to 0.8-1 which concerns me. this will go down in around 2 days back to the 0.03-0.06 ranges. It stays pretty constant until the next water change.

Most do water changes to decrease phosphate but here I am spiking mine. Im concerned for the health of the corals as they are obviously not happy about the spike. Should i be worried or just let it ride out? anything I could do to make the levels more stable? Im not sure if this much of a spike during a water change is normal.

It’s possible that in stirring the sand, phosphate that has precipitated or adsorbed by sand particles is resuspended. It is this suspended material that dissolves during the test that produces the high phosphate numbers. Filtering the water sample with a 0.45 to 0.22 micron syringe filter before testing should eliminate these particles and eliminate the apparent spike in phosphate.

 

[vetteguy53081]

how can a water change cause a false reading? I changed about 2 l of water (no stirring or whatever) and it went from 0.11 to 0.18
I’ll check again today to see if this has gone back to 0.11

As just indicated- stirring of sand and sediment often causes false readings and the settling will allow true readings. This is often responsible also for false ammonia readings where one does a water change and ammonia suddenly very high.
Other would be faulty RODI cartridges which have expired and use of tap water

 

[jda]

Hannah uses a light to do the test. Any time that you have particles in the water, the test will not be all that accurate. I would not use any Hannah test for a day or two after you stirred anything up.

Nevermind - the folks above me got it.