Ive currently got 0.45ppm phosphate and 20ppm nitrate tank is mixed reef with quite a few acros and a decent bioload.
I need to choose the best way to manage my nutrients.
What is the need you're referring to?
Have you not seen any awesome reefs with levels that high? Go looking – they are out there and fairly common. Steinhart Aquarium where they have breeding Acro's is a relatively famous one if you need a place to begin the search.
It's hard to think about at first if you're plugged in to the collective wisdom that nutrients are somehow harmful....but
nitrogen and phosphorous are not toxins. Far from it....N & P are two of the primary nutrients that every cell in your reef tank is made from; P is one of the most crucial elements in the process of photosynthesis.
So not only are N and P not problems, they are absolutely crucial elements of success in a reef tank.
If you remain patient you'll find that they are not a problem at all.
The only thing worth worrying a little is whether nutrient levels are climbing because your reef isn't growing for some reason (yes) or if nutrients are rising due to the waste of food in the tank (maybe). Once those boxes are checked satisfactorily, there's likely nothing more to worry about.
So if your reef isn't growing, it would be due to competition for some other nutrient being used up OTHER than N and P. (Leibig's Law applies.) The primary (and possibly only) suspect of Competition With The Reef would be your refugium. Let us know if there is anything else in your filter and cleaning arsenal that might also be competing.
As for food waste, that's the fastest way to make N & P skyrocket since food is (obviuously) loaded with primary nutrients. So if you are broadcast feeding anything, stop. If you are feeding more than your fish can eat before food drifts into the sand, rocks and filters, stop doing that too. Try to feed no more than one bite per fish at a time.....like you're feeding a baby. (Difficult in a tank with many fish....a good reason to keep bio-loads smaller. Still doable.)
If you stop wasting food and take the competition off your corals, you should see the N & P numbers steady up and then start to fall.
That said...can you tell us more about your tank? Like...
...how old is it
...how big is it
...how is it cleaned and filtered
...what are the rest of your water test numbers like
...what fish do you have
...can you post a full tank pic so we can see how things are growing in the tank?
We really haven't had enough information to give much in the way of specific recommendations without some more background. But you'll notice GFO didn't come up at all so far.....no reason for anything like that as far as I can tell.
