high phosphates?

[heigl22]

My phosphates are at a crazy high level, yet my nitrates remain acceptable. Any idea what would cause this?

 

[joshkirkland83]

Lots of things. Water source, food etc.

 

[heigl22]

Type of food? Or amount? If I am using rodi water, does the source matter? I just always assumed that phosphates and nitrates were pretty Much linked, if one goes up, the other matches it in proportion. I am guessing this not always the case?

 

[sc50964]

Phosphate comes from the waste of food and gets absorbed by substrate and rocks, which then will leach out the absorbed phosphate back into the water slowly and gradually. Doing WC will only remove the PO4 in the water column, but will not alter what's in the rocks and sand one bit.

 

[Randy Holmes-Farley]

What are the values?

Could be a number of things, but most likely for a true imbalance is nitrate reduction using things like denitrification in low O2 regions which uses a lot of nitrate and very little phosphate. Might also be new rock contaminated with phosphate.

 

[Alan Sunshine]

My RO/DI systems for water changes and ATO have TDS=0. I measured PO4 in RO/DI water and got .02 and .04 respectively. I know that measuring PO4 in RO/DI water is inaccurate, but are these acceptable levels? I am fighting a 0.16 PO4 lever with GFO, refugium, and 15% weekly water changes.

 

[Randy Holmes-Farley]

My RO/DI systems for water changes and ATO have TDS=0. I measured PO4 in RO/DI water and got .02 and .04 respectively. I know that measuring PO4 in RO/DI water is inaccurate, but are these acceptable levels? I am fighting a 0.16 PO4 lever with GFO, refugium, and 15% weekly water changes.

Accurate or not, those levels are not a problem. I discuss that exact issue here:

Aquarium Chemistry: Phosphate And Math: Yes You Need To Understand Both

Foods are by far the most important source of phosphate in most aquariums. In considering whether sources of phosphate other than foods are important, one must carefully look to the actual amounts involved to determine whether other sources are even worth trying to minimize.

reefs.com

Comparison of Food Sources of Phosphate to Other Sources
What about other sources of phosphate, like the “crappy” RO/DI water containing 0.05 ppm phosphate? A similar analysis will show it equally unimportant relative to foods.

Let’s assume that the aquarist in question adds 1% of the total tank volume each day with RO/DI to replace evaporation. Simple math shows that the 0.05 ppm in the RO/DI becomes 0.0005 ppm added each day to the phosphate concentration in the aquarium. That dilution step is critical, taking a scary number like 0.05 ppm down to an almost meaningless 0.0005 ppm daily addition. Since that 0.0005 ppm is 40-600 times lower than the amount added each day in foods (Table 4), it does not seem worthy of the angst many aquarists put on such measurements. That said, tap water could have as much as 5 ppm phosphate, and that value could then become a dominating source of phosphate and would be quite problematic. Purifying tap water is important for this and many other reasons.

 

[Alan Sunshine]

Loved the article and thank you for your response!! In order to remedy this 0.16 P04, I feel I need to be patient with the GFO (Bulk Reef). 3 questions: 1) what is the best Phosphate remover?, 2) how often do you change it?, 3) what is your desired P04 level for a mixed reef?