Where is the #%$@ phosphate coming from?

[DEdvalson]

Hi all,

I have a 90 gallon planted freshwater tank. All of the water parameters in it are pretty good except for the Phosphate level. The phosphate level is off the scale of a LaMotte Low Range Phosphate test kit. By diluting with RO/DI water, I am able to determine a phosphate reading of somewhere in the range of 20-30 ppm.

I can't figure out what the source of all this phosphate is. All of the water I use is RO/DI water, which I have tested and it has 0 phosphates in it. I also mixed up a gallon of water with all of the additives that I use, and still came up with 0 phosphates. Yet the water in my tank is off the scale.

Can anybody suggest anything??

Thanks,

Don

 

[MyShrimpDied]

Do you fertilize?

~ MyShrimpDied

 

[DEdvalson]

I do fertilize using FloraPlan. However, I added some of this fertilizer to some RO/DI water and then measured the results and saw no Phosphates. I have done this with all of the things that I add to the water.

Thanks

Don

 

[Cearbhaill]

Something you are feeding?

 

[DEdvalson]

Good thought on the food. I guess I'll test my food next.

 

[lark]

Are you doing anything to increase the hardness of the water? What is the PH? Above a pH of 8, phosphate becomes soluble in water.

 

[DEdvalson]

I am using Kent Marine RO Right to increase the hardness a little bit, however I am leaving it pretty soft. The pH varies from 6.8-7.2 depending on the time of day.

Thanks,

Don