trouble keeping newer clams alive

Exterminaans

New member
This is going to be long. I want to give people as much info as possible and will list tank parameters at the end along with equipment not mentioned in the course of explaining the trouble. But to start with, I've got a 29 biocube with Radion XR30W Pro Gen 3 LEDS - bought shortly before the XR15s came out or I would have gotten those instead. I've been running the Radions at 100 percent and although never had any problems, that's probably WAY too high for the size tank I have, I now realize. <---Any opinions on that would be welcome.
Ok so I am newer to clams, but have been reefing on and off for 10-15 years. This last stint (about 4 yrs straight) has been my most successful, and I've had a Deresa for probably the last 2-3 years, and it has grown from about 3 inches to probably 5-ish.
I had a tank crash around the first of October - basically I got busy/lazy over the summer and let the tank got one or two water changes too late and lost 3-4 larger coral colonies (I had no fish at the time; corals are my primary interest), most of my inverts, etc. Maybe not relevant to this but I just want to put it out there that there WAS a recent tank crash. If you guys want more details about what I did to recover, I can provide those. Long story less long - parameters have been stable aside from some difficulty with getting alk/dKH/Mg in line, since about 3 weeks after the crash.
I decided to get a maxima clam in I saw in the LFS, and added it to the tank. I acclimated it using drip method (which I have since determined may not be the right way to go), and it kept moving around, tipping over, etc, and would not attach, and then died probably about a week later. All params seemed fine, nothing way out of wack, so a bit later I ordered a Maxima and a Crocea from Live Aquaria, and while still using the drip method, this time I figured it was poor lighting acclimation that killed the first one, so I set the acclimation timer on the Radions to 4 weeks starting at 35%. The Crocea died within about 2 days, never attaching either, but the Maxima survived until this morning and did attache to the shell I placed it on. In the meantime, I pinged Live Aquaria and they told me they would ship a replacement for the Crocea, but we should wait to ship until the 14 day period was up because they can only reship once per order. So that put it arriving last Tuesday, the 28th. In the interim, I did some research on acclimation, and came across this thread: http://www.reefcentral.com/forums/showthread.php?t=1959576, which was so well presented it sold me.. The replacement Crocea arrived and I made sure temp and salinity were matching and then transferred it. So it was in floated in the tank for about an hour, in the sealed bag, for temp, then put straight in the tank after a salinity check. I reset the light acclimation, and it seemed fine.
Today i woke and the Maxima was dead. It had stayed in its spot (on a shell at the bottom), attached, but was not opening up as much as it used to for about a week. I would come out in the morning before lights on and it would look normal, and then open a bit more when the lights cam one, but then a few hours later, it would be nearly closed, with some of it's mantle extended, starting about a week or so ago. Remember that on Tuesday after the Crocea arrived I reset the acclimation timer, and saw not much change in the Maxima, so I moved it out a bit from it's spot between two rocks, thinking maybe low flow was the issue and saw an improvement within a few hours. So I thought the problem was solved.
Also know that both Croceas were both at about 2 inches, but the Maxima that just died was definitely under that, around 1.5, so I have been adding Reef Chili and some Phyto Feast daily.
The Maximas were all placed at the bottom of the tank on a shell, the Croceas all placed about 3 inches up on a rock. I'll include par readings for both spots, which I have just taken, so the acclimation timer is running the lights at 35%. Lights come on at 3pm and shut off at 1am.
As I was testing parameters tonight (I've been testing every other day since the tank crash) I noticed that the Crocea had detached and moved itself under an overhang, so now I'm worried about it.
If the latest Maxima death was due to to drip acclimation, would it survive for 2-3 weeks after that? Do clams know exactly where they are moving to, meaning, did the Crocea move under the overhang to avoid light/flow, or do they just bumble around until they find a spot they like? Are there any accurate, practical measurements for flow recommendations for clams? I'm frustrated with terms like, "not much, moderate, low", because those are all relative terms and can mean vastly different things to different people.

I'll list my parameters, with some indication of their stability now. I realize that alk/CA and MG are not ideal, which is not my goal, but that should just inhibit growth, not lead to death, right?

Salinity: 1.024 - rock solid since the recovery
Temp: 79.4 - solid
Calcium: 405 - hit a low of 360 on the 17th so I've slowly been increasing it to 450
dKh: 9.3 - this spiked to 11.2 for some reason around 11/17, and I've been slowly decreasing it to 8.4 on the 29th, but has risen to 9.3. Not sure why as I have not increased it.
pH:8.28 - fluctuates about as much as you might expect. Nothing wild or major.
Mg: 1365 - this too hit a low around the 17th - slowly increased since but now it's to high so I pulled back a bit tonight
Ammonia: According to my Seneye this is at .001 - solid since crash recovery
Nitrates/Phosphates both: 0 - solid
PAR: lights at 35% acclimating to 100 - current reading at the Crocea spot was 260-290, reading at the Maxima spot was 125-150.
Pumps - aside from the biocube circulation pump, I'm running 2 Echotech MP10s set at about 40-50% speed on a combination of reef crest/tidal swell/lagoon for 5h, 4h, 5h, respectively, starting at 8am, and after that, at a reduced "nighttime speed" of 20% constant.
 
Are there any fish that are bothering the clams? Also, where was the Maxima from? I've had bad luck with all of the Tahitian Maximas.
 
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