Why does my Phosphate level continue to move to zero despite dosing

[Randy Holmes-Farley Verified Community Expert]

All photosynthetic organisms need phosphorus. Algae is one user, but eliminating it may not eliminate the need for dosing.

 

[SteedC]

What brand and size is your skimmer? Just curious because I had a skimmer that was too large for my tank and it was sucking everything out making it almost sterile.

I have the Reef Octopus CLASSIC 202-S 8"

 

[JCOLE]

I have the Reef Octopus CLASSIC 202-S 8"

Nice skimmer! I have the Reef Octopus 200-INT. Do you have the 133 gallon tank? If so, then you might be skimming too much. See rating from Reef Octopus for that skimmer.

Filtration Handling

265 Gallon – Light Filtration Demand

200 Gallon – Medium Filtration Demand

180 Gallon – Heavy Filtration Demand


Does your skimmer run 24/7? Is it skimming wet or dry? If so, you could try 12 hours on and 12 hours off and skim dry for a couple weeks to see what happens.

A skimmer will almost make your water sterile if it is too big and skimming too much.

If nothing changes then you might need to start dosing Trisodium Phosphate.

 

[SteedC]

Yes, I do have the 133 with the 32 gallon sump. I am skimming pretty dry right now, but I will try and do the 12 on and 12 off. I got the 202- S because the 150 seemed too small based on what BRS was saying so I went with the next largest they had, sounds like I may have went too big.

 

[FishyDP]

Agreed that running chaeto and an overrated skimmer may be depleting your system of nutrients. Your "ecosystem" appears to need some balancing, in the area of nutrient import/export. You could try putting your skimmer on a timer, and run it say 12 hours a day. You could also try reducing the photo period for your chaeto, or removing a large chunk of it...or a combo of all of the above.

What is your feeding schedule like?

 

[JCOLE]

Yes, I do have the 133 with the 32 gallon sump. I am skimming pretty dry right now, but I will try and do the 12 on and 12 off. I got the 202- S because the 150 seemed too small based on what BRS was saying so I went with the next largest they had, sounds like I may have went too big.

It's better to go bigger in my opinion. This way it will handle the load as you add more and more corals. . What test kit are you using for phosphates?

 

[SteedC]

Agreed that running chaeto and an overrated skimmer may be depleting your system of nutrients. Your "ecosystem" appears to need some balancing, in the area of nutrient import/export. You could try putting your skimmer on a timer, and run it say 12 hours a day. You could also try reducing the photo period for your chaeto, or removing a large chunk of it...or a combo of all of the above.

What is your feeding schedule like?

I feed 3 times a day. Morning pellets (auto-feeder), late afternoon black worms or LRS reef frenzy, evening pellets (auto-feeder)

 

[SteedC]

It's better to go bigger in my opinion. This way it will handle the load as you add more and more corals. . What test kit are you using for phosphates?

I am using a Hanna Phosphate tester

 

[SteedC]

It's better to go bigger in my opinion. This way it will handle the load as you add more and more corals. . What test kit are you using for phosphates?

Well, I did spend all weekend on the WWC live sale and did pick up 9 new pieces of coral so....

 

[JCOLE]

I am using a Hanna Phosphate tester

I use the same one. I have the High and Ultra Low reader. I use the Ultra Low and it is near spot on. Just tested mine last night and it was around 0.30. It is high but my corals seem to be responding to it well so I am not worried too much.

 

[JCOLE]

Well, I did spend all weekend on the WWC live sale and did pick up 9 new pieces of coral so....

That should help. I didn't catch if so but do you feed your corals? If so, what do you use and how often?

 

[SteedC]

That should help. I didn't catch if so but do you feed your corals? If so, what do you use and how often?

I feed them Reef Chili about 3 times a week

 

[Mike N]

@SteedC How are your parameters looking now?

I'm dealing with the same issue (phos undetectable) and I am not running chaeto or a skimmer at the moment.

 

[SteedC]

@SteedC How are your parameters looking now?

I'm dealing with the same issue (phos undetectable) and I am not running chaeto or a skimmer at the moment.

Hi Mike, My parameters are better now. 4 Nitrate and 0.03 Phosphate. I'll tell you the things I did that I THINK got me there.
1) I reduced my Refuge light down to 4 hours a day
2) I added about 8 pieces of new coral and 2 fish
3) I only run my skimmer 12 hours a day (this was the last change I made) I started seeing sustained Nitrate and Phosphate after this change.

Good luck! Of course now I am dealing with Cyano

 

[Mike N]

Hi Mike, My parameters are better now. 4 Nitrate and 0.03 Phosphate. I'll tell you the things I did that I THINK got me there.
1) I reduced my Refuge light down to 4 hours a day
2) I added about 8 pieces of new coral and 2 fish
3) I only run my skimmer 12 hours a day (this was the last change I made) I started seeing sustained Nitrate and Phosphate after this change.

Good luck! Of course now I am dealing with Cyano

Great, thanks for the information

 

[Randy Holmes-Farley Verified Community Expert]

Crap! Ok I'll try pulling the chaeto and see if that works.

Dosing and running macroalgae has benefits not mentioned, like O2 and pH raising st night when you need them most. IMO it is a fine plan.