SPS issues

[coralor]

I have a question for you SPS pros. I apologize upfront for the length of my post.:spin3:
I am fairly new to having success with SPS and am not quite sure why some of my pieces are only coloring up on the tips and are still remaining brownish below that.
My tank is about 2 years old and I have had to work through an assortment of issues to get to this point. Mostly newbie errors, lol)
I now have some very beautiful pieces and all are definitely growing. The majority are fine, but a few only have really nice colors at their tips- the lower parts are brownish. And I have also noticed that on the underside of some other corals they have slowly receded (necrosis?) even though the upper side is very healthy looking. Could this be from lack of light or flow and is this normal?
One thing I observed was that after it had been suggested to me that perhaps I wasn't feeding the corals enough and I did increase their food, they responded with faster growth and better polyp extension. But the very slow necrosis still occurs on some. The odd time it occurs rapidly, but that doesn't happen very often anymore.
I have always struggled to get the Coraline algae to grow well in this tank and assumed this was from the too little flow and the detritus that would build up on the rocks as a result. Since that issue has been addressed (a few months ago thanks to some of you) my flow and water clarity have greatly improved. Though if I use a turkey baster I can still stir up quite a bit of detritus from the rocks.
Of interest to note, I have had some issues with my RO/DI system over the last few months and the TDS readings had gone up for a while. I have noticed issues in the past with the SPS when this sort of thing has happened before...
My other parameters have all been well within range and stable for some time- about a year now.
My DT is 105 peninsula design with a large amount of rock (lost track of how much a long time ago, lol and a 40 gal sump. I run a JNS U3 protein skimmer (recent replacement of my Reef octopus skimmer) a GFO and currently manually dose for calcium, magnesium and alkalinity with a 2 part solution as required plus Red Sea's No3 PO4 x to help keep the phosphates low. (Have a dosing pump I need to get back on line....)
I try to do biweekly water changes of 20% but have admittedly been lax on these the last 3 months or so.
For lights I use 4 Kessil 160's along with Maxspect Razors. They are all on timers.
I would greatly appreciate any suggestions and help and thank you in advance!

 

[DubiousMaximus]

Many acro sp have brown, tan & green tissue on the older stalks while only the newest growth have color. The under-sides receding could be from shading. IMO, most overlooked aspect is the size of mature colonies while placing frags and micro colonies so they don't cut light from those below. LEDs seemingly cause more of a shaded affect than other types available from what ive seen and read.

That's the benefit of a mature tank, less water changes due to stable nitrogen cycle, you'll probably get away with doing w.c. only when NO3/PO4 reache above avg levels.

 

[coralor]

Thanks for your response, DubiousMaximus
I have done some more research here on the issue of recession and think maybe it could be due to a recent change in GFO media. I added a bit more than usual and I was in a bit of a rush so probably didn't rinse it well enough either.
I didn't realize that LED's were more likely to cast shadows. Is there a better lighting system you would suggest I might consider adding or changing to in the future to help eliminate the shadows?
Most of my corals are really not that huge yet so as to cover up the lighting for each other.
Ideas for increasing coralline algae? Purple up was recommended to me but I am hesitant to add it until I get the recession issue fixed. And should I turkey baste the rocks to get rid of the detritus on them or might that contribute to the SPS issues?

 

[mcfa2403]

I am not really an sps expert but I can answer a couple of your questions.

-For lighting, if you like the LED look usually the best way to eliminate the shading effect is to supplement with T5s or be particular about your coral placement.

-Detritus should be eliminated in an sps tank, mostly because it indicates flow issues. Siphoning the detritus during out is the best way to remove it. To eliminate future detritus I would either go with a lighter rock stack (You will notice many great sps tanks have relatively little rock) or would increase the flow and would highly recommend using a controllable pump as pulsing features seem to aid in detritus removal.

-For coralline I would not recommend purple up as it will throw your dosing off (it is mostly calc/alk) but woulod instead maintain a steady calc/alk/mag ratio. Keeping these levels stable is critical to coralline growth. The higher all 3 are the faster it will grow, but be careful raising them and do it very slowly keeping an eye on your acros to watch for alk burn on the tips.

 

[coralor]

Thanks for your response)
I have recently had a much better system for flow in my tank- thanks to some members' help on a prior post where I learned that it wasn't such a good idea to have my MP40 on the opposite end of the tank as the overflow with return. I have since removed the MP40 and added 2 Jebao wavemakers on either side of the overflow with much better results. The only problem now is how to stop the sand from being stirred up too much on the peninsula end while still having the detritus cleared up at the base of the overflow...
But I definitely need to do some siphoning then. I will try a 1/4" rigid tube on the end of an airline hose so as not to disturb my acros too much.
And you have me thinking about adding some T5's. I would like to measure the par levels first but haven't done enough research to be able to find a decent par meter for a decent price... Remember, I am Canadian, eh? And its sometimes tough to find something that fits the bill, so to speak
How high would you recommend going with the calc/alk/mag? I have had too high alk in the past and experienced the burnt acro tips for sure.
My params are posted above.