phosphate removal

[dmolavi]

I have started noticing brown algae is spots of my tank...did a quick check and sure enough, phosphates. Since I do weekly PWC, whwt is the next best way to control them? Phosguard?

Also, on a 56 gallon tank, are additional circulation pumps recommended, besides the flow from my 2 HOBs pushing 400gph?

 

[fort384]

What level are your phosphates at? Is this a planted tank? How are you lighting the tank? What are you feeding and how often/how much?

 

[dmolavi]

Phosphates are around 0.5-1.0ppm (based on API test). It's very lightly planted with some Amazon Sword and 3 other plants (that I can't recall ATM). Tank is lit with a 24" PowerGlo fluorescent tube @18000K. I'm feeding flake food once daily, about 1 - 1 1/2 tsp (it's all gone within 60 seconds).

I'm filtering with 2 HOB filters @200gph each, with floss and carbon in each. One also has 50 micron microfiber, the other has 2 100mL Purigen pouches. Water is crystal clear

 

[fort384]

I would cut back feeding a bit - feed 2 out of 3 days or so. That will help bring the PO4 down some. You want somewhere around 0.5 if you plan to keep plants, so you aren't far off. I wouldn't recommend running any additional chemical filtration until you try cutting back the feeding a bit.

Lighting is a little on the high side color temp wise, you are missing some red peaks in the spectrum that plants need with a color temp that high. Probably not an emergency situation, but next time you replace the bulbs, I would bring it down to 6500-10000K.

 

[dmolavi]

I'll try that on the feeding.

As for the lamp, the color spectrum is attached; looks OK in the reds, but I will check a lower temp bulb next time around.

Also, what about circulation? Are the 2 HOBs enough (run aft to fore in the tank), or should I add a lateral powerhead to make sure no dead zones are present?

 

[fort384]

I think you are fine with just the HOBs.

There are some reds on the lower end, but a ~6700K bulb is going to have peaks in the reds with higher wavelengths above 700, and also less on the blue end.

 

[dmolavi]

Awesome, thanks. I'll keep an eye on things and see how it goes (I track everything in my tank in a pretty detailed spreadsheet, so I should be able to see the change, if any, fairly quickly once it happens).

 

[fort384]

Excellent, let us know.

If the reduced feeding doesn't bring it down, there are some chemical options out there... but you are so close, I wouldn't resort to it yet. PO4 is removed usually via granular ferric oxide (GFO), which is not cheap.

 

[dmolavi]

Yeah, I don't want to have to resort to a GFO reactor (tank isn't drilled, so I would have to create a siphon powered sump...which I am very leery about).

PhosGuard seemed to be the next best option, as I have always had success w/ SeaChem's products. I will do my weekly PWC tomorrow and start the new feeding regimen tomorrow as well. Time shall tell

 

[fort384]

I think phosguard is just low grade gfo. Gfo could be run in a bag in your HOB.

 

[fort384]

Also check your water source. Local water sources can sometimes contain low levels of phosphates. Especially if you are in a rural area or farming community.

 

[dmolavi]

Good call..I haven't checked the tap. I plan on getting a RO/DI for an upcoming SW build, so I could always make the switch.