refugium size to reduce Po4, No3.

[boxfishpooalot]

Hi guys,

Im contemplating what size refugium to add. I have a 125gallons fowlr. There is a ton of fish in there that are pigs and they eat too much. about 16fish total.

I already grow macroalgae in my sump that has limited space, especially in height. Only has about 10" of water in it.but it does not help with nitrates and phosphates very much. My goal is 0 for both.

Im thinking a 300gallon container with a 400watt metal halide to grow macro algae. The problem with my fuge now, is the caulerpa raecmosa grows up towards the light. Then it hits the top of the water and turns yellow at the surface where leaves are exposed to air.

I also grow chaeto. and some red caulerpa looking stuff. slow growing though.

So, you think 300gallons of water with 400watt halide will reduce 1-3ppm of phosphate, and 100+ppm of nitrates? and keep it there?

Thanks Box

 

[Samala]

Wow.. I think a 300gallon refugium is going to dramatically dilute down the typical nutrient levels you have in your tank to start with. Its going to make a huge dent in the numbers based on that alone.

A few questions.. how big is the fuge now? What sort of lighting is over it? And are you aggressively pruning the 'fuge plants, or just letting them get to large sizes and pruning irregularly?

I'm not sure that a larger volume is necessarily going to sink nutrients faster. There might be other ways than loading your system with such a big satellite tank. (Unless of course its your dream to maintain 425 gallons.. )

>Sarah

 

[boxfishpooalot]

how big is the fuge now

It 3.5ft long, with about 10inches of height for water, only a foot wide(40x10x12). But the macro can only grow in about 1.5feet of it due to pumps in the way.


What sort of lighting is over it

400watt metal halide 4200k.

And are you aggressively pruning the 'fuge plants, or just letting them get to large sizes and pruning irregularly

I take a snip every day to feed the tangs, but it outgrows their feeding habits. And I throw out a half bucket full every 2months or so.

Fwiw, I like the large size, although impracticle. I just want to have enough room to grow so much macroalgae that they reduce all nutrients to zero, and keep it that way.

 

[Samala]

Gotcha. If you like having a big volume, more power to ya. I just think you could get away with something quite a bit smaller if you encouraged the plants to grow rapidly -- perhaps through dosing a little iron, as you've got the other nutrients that are often lacking (N, P) - and acheive your goal in another way.

Every two months taking out a 5gallon bucket's worth is pretty decent, but no where near as fast as Caulerpa racemosa will grow given good environment. Your lighting sounds like more than enough, but with 10x12x18" for room to grow thats the big limiting factor. But you knew that.

I'm still thinking you could prune more frequently, dose a wee bit of iron perhaps to see if that aids the plants growth, and go from there. I also wonder if this area gets stagnant with all the macro in the chamber? Extra pumps, even just air driven water movement from large stones or bubble curtains could make a big impact in encouraging exchange of nutrients and gases near the plant leaves/fronds.

I havent run large bioloads with large macro/seagrass populations yet but judging from their nutrient uptake rates I'd say even a modest sized fuge should keep up with nutrients from quite a large number of fish. Thats just my gut feeling though, based on the numbers I see from the tanks.

Still, I certainly wouldnt be the one to tell you no if adding the fuge is the goal. As I said, it'll have a huge effect on nutrient levels through dilution alone.

>Sarah

 

[boxfishpooalot]

well for now I raised the sumps water level by 10gallons. Which gave me an extra 5" of height. Now the caulerpa can grow without reaching the top.

Im think im just going to let it grow to a huge ball, the chaeto, and let the cualerpa grow large too. This way nutrients are removed faster.

I also dose iron. Its seachems flourish iron(iron gluconate) but im not sure how bioavailable it is to macroalgae.

Do you really think macro can become Co2 limited? That seems strange to me when low ph in my house is easy to attain by closing the windows. Currently its 8.10 with the windows open. If I close the windows it can get as low as 7.8.