Some coral questions

[SJimmyH]

I have a nice medium sized frag of pocillapora. This is a coral I have had in the past, but never one as large as this.

I find it very hard to place in a location where the entire coral gets light. Due to the light fixture placements, I can give about 75 percent of the coral direct light. The rest of the coral (mostly the base and around it, is shaded by the larger head of the coral. I now am noticing that after about 3 weeks in the tank, this area around the base is starting to recede.

One, should I worry about these shaded areas? Is it normal to have these areas die off?

Secondly, and more in my expertise area, I have a question about Blastomussa. Although I have kept a vast number of LPS species, this LPS is one of them that I have only a little. I own a frag around 2.5" in diameter. Been doing great. Has eaten mysis shrimp. Good color.

Over the last 2 days a few of the polyps in a localized area have closed up and not opened at all during the day. The rest of the polyps are acting normal. I know many species of coral can go through periods of lackluster just to open back up again after a short time. Do Blastomussas do this too? Again, its not the entire coral either, just a small section of like 4 polyps.

Anyhoo, thanx ahead of time.

Oh, specs in the tank are great. I have no readable unwanteds and all readings are within most recommended optimum levels. All other species thriving.

Additions include, kalkwasser drip, Phytoplankton, Iron (in small doses for fuge), Iodide when levels are low, regular weekly sediment bacteria doses and fish food.

[theatrus]

Recession is not always light related, and a receeding base is usually a bad sign. What is the flow around the area of the coral/tank total? What lighting do you have currently?

[cook]

Also check your alk/ca swings. This cause recession at the base.

[SJimmyH]

My alkalinity is fairly stable dropping maybe 1 dkH over the course of a week or more. Calcium drops even slower.

Current readings: 12 dKH and 440

2 150W MH lighting about 8-9 inches off top of water. Poci is at the top of the tank, maybe 6 inches from surface at top and 8 inches at base. Lighting is 7 hours a day with actinic T5 suppliment for 3 hours on either side and during the MH schedule. Blasto is a little lower about midway depth which is around 10-11 inches from surface.

Speeking of the Blasto, the polyps that were closed are now starting to open, but there seems to be a new area of the coral that is now closing up during the day... this is leading me to believe its just normal coral behavior. Anyone think differently?

My flow in the tank is pretty high. 75 gallon tank with about 650 gph from main pump and overflow. Two SEIO M1100 pumps with controller. From 1100 to 2200 gph flow depending on the pump speed at the time. Skimmer pump may add in another 100-150 gph too.

Coral placement (for the Poci) is such that I am giving good crossflow without any direct current from powerheads or main return lines. Particles in the water may flow around the coral at a rate of ~3-4 inches per second or maybe even faster.

Let me specify that the Poci recession is not rapid or is it very large. The coral not directly exposed to light (or shaded) tends to not extend much if any (which includes the vast majority of the base), while the portions that are exposed extend quite a bit.

[rigleautomotive]

can it be getting burned by another coral.sweepers or chem war fare

[capn_hylinur]

Originally posted by SJimmyH
My alkalinity is fairly stable dropping maybe 1 dkH over the course of a week or more. Calcium drops even slower.

Current readings: 12 dKH and 440

2 150W MH lighting about 8-9 inches off top of water. Poci is at the top of the tank, maybe 6 inches from surface at top and 8 inches at base. Lighting is 7 hours a day with actinic T5 suppliment for 3 hours on either side and during the MH schedule. Blasto is a little lower about midway depth which is around 10-11 inches from surface.

Speeking of the Blasto, the polyps that were closed are now starting to open, but there seems to be a new area of the coral that is now closing up during the day... this is leading me to believe its just normal coral behavior. Anyone think differently?

My flow in the tank is pretty high. 75 gallon tank with about 650 gph from main pump and overflow. Two SEIO M1100 pumps with controller. From 1100 to 2200 gph flow depending on the pump speed at the time. Skimmer pump may add in another 100-150 gph too.

Coral placement (for the Poci) is such that I am giving good crossflow without any direct current from powerheads or main return lines. Particles in the water may flow around the coral at a rate of ~3-4 inches per second or maybe even faster.

Let me specify that the Poci recession is not rapid or is it very large. The coral not directly exposed to light (or shaded) tends to not extend much if any (which includes the vast majority of the base), while the portions that are exposed extend quite a bit.

the major consensus on this site would be a high of 10.5 for dkh---after that experienced guys have noted problems with corals then

[SJimmyH]

Of course, this could be possible, but it isn't near anything else. I also haven't observed any of my corals sweeper tenticles extending much more than a few inches.

The Blasto is the nearest coral to the Poci. So, I guess I can observe this specifically since these are the two corals I have questions with.

Water flow in this area tends to go accross each coral from the sides, while the blasto is lower in the tank than the Poci. Current wouldn't be carrying chemicals or pushing any sweepers from the Blasto (does this species even have sweepers?) towards the Poci.

Hey, you know what? I just thought about it, but the small little pebble that the poci was attached to when I got it had a couple star polyps on it. Being that they were there when I bought it I didn't think much of it. I have never known star polyps to attack anything. What do you guys think?

[SJimmyH]

Originally posted by capn_hylinur
the major consensus on this site would be a high of 10.5 for dkh---after that experienced guys have noted problems with corals then

I haven't. I've been doing marine tanks longer than most around here. As a matter of fact, I have never seen anything that made be believe alkalinity has much of a direct effect on anything. All I really even monitor it for is to ensure that I have carbonates available for corals and corallines to use for skeletal structure and to pre-empt any swings in pH or Calcium.

Besides, I have elevated CO2. I would much rather keep a 12 dKH alkalinity than a 7.9 pH (which is near what I would be if I dropped to around 10 dKH).

I don't mean to be an arse. I just honestly have never seen anything die directly from alkalinity problems. Now, if those alkalinity problems lead to pH problems... then I agree, it would be bad. Who knows though... we are learning all the time. I could be messed up.

[SJimmyH]

Sorry, capn_hylinur, after reading that last post I realize I came accross badly. I am the one asking the questions, and you are trying to help. I may not agree, but I don't want you to feel you can't voice your opinions either. Hope I didn't torque you off.

[capn_hylinur]

Originally posted by SJimmyH
Sorry, capn_hylinur, after reading that last post I realize I came accross badly. I am the one asking the questions, and you are trying to help. I may not agree, but I don't want you to feel you can't voice your opinions either. Hope I didn't torque you off.

Hey I'm into abuse anyways(JUst KIdding)

In no form did I take it that way---I joined this site because I realized I have been a victim of many misconceptions--therefore appreciate the variety of opionions and expertise offered here.

that statement comes from a previous poster(alot of expertise) I'll see if I can find it again.
Scott

[capn_hylinur]

Here you go;
check the comment by JP from NY (he's a moderator)

http://archive.reefcentral.com/forum...readid=1137502