SPS growth has been good, I have huge colonies for some of them . I just feel like it could be better as I can easily keep nitrates between 15-20 without doing anything. So if i can keep phos lower I would be happy.
There really is no great reason to have P lower UNLESS it's from corals using it up! :)
You mentioned good growth, which is excellent but not without its costs...will point to this later.
main tank is 180g tank
6 mp40s
frag tank is 70g
4 mp10s
sump normally holds about 40g at regular level. flow through the sump is 700gph.
I am not hurting for flow.
Well...from the numbers (both $ and GPH) you'd think so, but trust me that it's at least worth an in-tank review.
I assume the frag and display are connected since you mentioned them together.
700gph is about (700/250=) 2.8X turnover...seems about right. 2x-4X is the usual recomendation, but more or less is also OK.
I'll grant you that 18,000 GPH from those six MP40's sounds like a lot of flow.
But this is the case I was describing where ultra-soft flow kinda "spoils" the GPH number....it's a lot of GPH, but it's
low velocity (weak), so it *takes more flow (GPH)* to do the job.
There are (at least) three factors you should look at IMO.
* One is that MP40's are strong out to about 24" from the pump, but quite weak past that. I see at least one or two on the back wall of your tank....not sure about the rest. Back wall is often good, but make sure they all have unobstructed access to the bulk tank water in front of them. Any obstruction within that 24" cone in front of the pump is a flow killer.
* Two is that you are probably running a program on the mp40's vs running them at 100% all the time. So on average that 18k GPH is probably more like 10,000 GPH....sometimes more, sometimes a lot less. During the down-cycle this can leave some zones of your tank starving for flow.
* Number three is the great growth you've had with your corals so far.
Corals will do a great job of blocking up their own flow as they grow out....so it's common for an SPS tank (branchy corals do this in particular) to become a "victim of its own success" when corals grow out enough to dampen and slow the overall flow in the tank. Once flow slows to below a certain velocity, the flow can't move particles or penetrate the corals boundary layer properly anymore.
At minimum a re-arrange of the tank's flow is probably called for, but it's possible that (even more) pumps will have to be added depending on your success with rearranging the flow you have.
IMO it looks like there's still lots of open space in your tank, so you "should" be able to reestablish strong flow if you had it before. But MP40's (and probably other similar pumps) do not do well in really crowded tanks in my experience...which corresponds with their ultra-soft flow being low-speed even coming straight from the pump. It has no "oomph" to do work if the flow encounters *any* obstacle.
There are still some pumps on the
market that generate stronger flow (not referring to GPH but to velocity) if you want to add something different or replace what you have.
the thing that hosed me is that I didnt realize that my phosphates were close to 3.0 in my 70g when i let it go after a crash and just kept it fish only while the 180 was being done. so it was just soaked into the full system when I combined the two tanks. I didnt think about the rock being a lasting issue when I did it.....
I'm not sure what you mean by hosed?
The amount of N and P coming into the tank with every feeding absolutely dwarfs the amount that would have been added to the 180 with the 70 gallon "from the rocks" and whatever else....IMO the joining might not really be that relevant.
Folks get freaked out about phosphates and nutrients in general, but phosphates literally hurt nothing as far as corals are concerned. P is a harmless nutrient. (The only harm to corals comes when you find P absent or near-zero.)
Even high nitrates (N), which are much more concerning in terms of potential side effects for corals than P, are unconcerning if they are relatively in balance with P and other nutrients.
That said, when the N&P levels are likely being driven by wasted food, there's usually a desire to eliminate that waste for the long term good of the tank. More on this...
Food wise I just buy every single pellet I can find and mix them into a big container and then fill up the auto feeders. which 2 lasts around 2 months probably? the frozen fishfood feeder is new but need to keep it going to keep my copperband eating.
everythings automated as I travel a lot for work.
That's a worthy method since you're out of town a lot, but also probably very sloppy since there's no way for you to really mind the fish and how they are eating.
For example, how can automation feed no more than they'll eat in a minute or two....or before the food disappears into the rocks, whichever happens first....and repeat that cycle until they're full?
Essentially impossible.
IMO you need flow that is not only OK for your corals, but flow that is *impeccable* to pull that off without excess wasted food breaking down in the system.
A strong protein skimmer would also be highly recommended if you aren't already running one.
I hardly recommend mechanical filtration for reef tanks, but this is a case where it could be well-warranted....something like a protein skimmer or roller-felt (or both) that actually pulls the waste *out of the tank* vs trapping it in a filter element *in the tank* is what I'd use. IMO first go big on the skimmer (if you haven't already) and if that still doesn't moderate things properly/to your liking after a month or so, then add a roller (or similar).
