excess phosphates?

john b.

Junior Poster
May 21, 2005
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I tested my phosphates today before adding macros and my phoshate level is higher then what I've added to the tank so far this week.In other words, I added about 2 ppm on Sunday and now the reading is well over 3 ppm.My tap doesn't contain any detectable amount and I deffinately don't overfeed my fish. I know I shouldn't trust the reading but would just like to know what in a planted tank can make phosphate levels go up? Is it possible that a peice of driftwood could do this? I recently read about contaminated Eco- Complete, but I have a flourite substrate.Thanks for the help,
John
 

Tom Barr

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Jan 23, 2005
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Re: excess phosphates?

It's most likely a cheapo test kit.
Most tanks eat PO4 like no tomorrow.

If you add CO2, KNO3, then you should see a lot of PO4 decline.
No, no substrate PO4 in flourite.

EC has issues, but PO4 really is not one of them. Light weight and large grain sizes are. I had hope for it initially.

Regards,
Tom Barr
 

oveb

Junior Poster
Jan 24, 2005
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Re: excess phosphates?

I experiensed exactly the same thing with my tank. It "eats" a lot more KNO3 than PO4. I add just below 10ppm NO3 and 1 ppm PO4 each day (1 W/liter MH) and PO4 rises to more than 5ppm in the end of the week. I have very few "starving" fish.

I only have Eleocharis Acicularis in the tank and uses JBL's droptests.

I find this a bit annoying...
 

groovyfishguy

Prolific Poster
Mar 31, 2005
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Re: excess phosphates?

oveb said:
I experiensed exactly the same thing with my tank. It "eats" a lot more KNO3 than PO4. I add just below 10ppm NO3 and 1 ppm PO4 each day (1 W/liter MH) and PO4 rises to more than 5ppm in the end of the week. I have very few "starving" fish.

I only have Eleocharis Acicularis in the tank and uses JBL's droptests.

I find this a bit annoying...

Whats the size of your tank and your co2 level?
 

oveb

Junior Poster
Jan 24, 2005
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Re: excess phosphates?

Here are some details:
KH4
Ph 6.3-6.4 (Aquamedic controller)
No driftwood
300 liter
9 Watt UV-C
Eheim 2028

I just changed 75% water and PO4 sank down to ~1ppm again.

The only small problem I have is that I get small amounts of cyano sometimes. Not a big concern of mine.
 

groovyfishguy

Prolific Poster
Mar 31, 2005
35
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Las Vegas
Re: excess phosphates?

oveb said:
Here are some details:
KH4
Ph 6.3-6.4 (Aquamedic controller)
No driftwood
300 liter
9 Watt UV-C
Eheim 2028

I just changed 75% water and PO4 sank down to ~1ppm again.

The only small problem I have is that I get small amounts of cyano sometimes. Not a big concern of mine.

Maybe a Guru will chime in but I found a thread on apc where tom said daily po4 consumption rates were .2ppm to .8 ppm so if you are adding 1ppm per day you will always have a buildup. even though a 50% water change will bring things back a bit maybe you should bump it down a bit?
 

oveb

Junior Poster
Jan 24, 2005
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Re: excess phosphates?

Sounds logical, it the huge difference in consumtion that puzzles me...

If I add 10ppm's of nitrat every day it's all gone in the end of the week, during the same period I add 5-6 ppm's of phosphate and almost all of it is still there after a week...

A bit strange I think...
 

Tom Barr

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Jan 23, 2005
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Re: excess phosphates?

I doubt it hurts adding that much.

But the tank does not need that much.
Hair grass grows pretty fast once well established........

I'd add more KNO3 and a bit less PO4 myself.
JBL test kits are not the most reliable, don't put too much faith into them unless you have calibrated them.

PO4 and NO3 hobby kits are fairly squirrlely.


Regards,
Tom Barr
 

oveb

Junior Poster
Jan 24, 2005
25
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Re: excess phosphates?

Thanks all !

I'm trying to calibrate an auto-fertilizer that's why this is so interesting to me.

I'll lower the PO4 dose and watch out for lightgreen spots.
 

srozell

Guru Class Expert
Jan 24, 2005
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Re: excess phosphates?

oveb said:
Thanks all !

I'm trying to calibrate an auto-fertilizer that's why this is so interesting to me.

QUOTE]

OOOOH! An autofertilizer!

Sounds like a toy I need to get. What are you using?
 

andrewmcleod

Junior Poster
Mar 29, 2005
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Re: excess phosphates?

oveb said:
Sounds logical, it the huge difference in consumtion that puzzles me...

If I add 10ppm's of nitrat every day it's all gone in the end of the week, during the same period I add 5-6 ppm's of phosphate and almost all of it is still there after a week...

A bit strange I think...

Isn't there a rough 10:1 N:p ratio for this? i.e. 10ppm of nitrate to 1ppm of phosphate? (accounting for the fact that fish food is heavy in N and light in P)