PH swing => RTN ?

[preef]

Came home to an RTNed Birds of Paradise today. It was fine yesterday and today it's gone with the exception of the very tips. I fragged a couple of millimeters off of three tips hopefully they'll live. That's all that was left.

Ever since the hot weather finally broke and we opened the windows and turned off the AC a few days ago my pH has been high. It is currently oscillating between 8.55 and 8.15 (day and night). Before we opened the windows it was oscillating between 8.1 and 7.9. Can the high pH and/or .4 swing cause RTN?

I lost a lot of corals in the spring when I treated a fish in the DT with Metro laced food. Either the meds or the heavy feeding caused a crash. Even long after the incident corals that survived the incident seem more susceptible to RTN. I lost a green slimer about a month ago for no apparent reason. The Birds of Paradise I lost today did lose some tissue at the very base but the rest of the coral grew nicely since then until today. All frags added after the incident are doing well without an RTN or STN incident.

Another change I made to the tank a few weeks ago was increasing the flow through my fuge. I realized the flow was too low and Nitrate rose about 5 ppm. Today it is 0.00. Perhaps the BoP liked the higher nitrate level.

Temp swings are minimal 0.5deg at most w/ controller. Dosing BRS two part (alk recipe 1) using dosing pumps once an hour.

Any ideas?

Tank parameters:
Nitrate 0.0 (no color change w/ salifert)
pH 8.56
Alk (dKH) 8.45 (I usually target 9 - 10. Increased my dose today)
Calc 420 (I targey 450. Increased dosage of this as well today)
Temp 80.1
SG 1.026
Mg 1245 (Target 1300. Time to make another batch of supplement)
Phosphate 0.00 Hanna Checker

Picture of pH swings over the last week:

 

[Mossrope]

the opening of windows resulted in higher oxygen circulation in the room, instead of an enclosed air con room depleting oxygen over time.
The change can be the reason that caused your ph to increase.
Secondly, from the graph ph has been gradually increasing through the week till the RTN occurred within that one day time frame,
so it can be the swings or it can be the high ph increase and even both as a joint attack on your BoP.
Day night ph swings given your figures are still quite acceptable but are you having a reverse light period for your sump or having a lot of marcoalgae(also a reason for ph swing) in the sump?
Controlling the last two factors can help reduce the ph swings.

apart from the above...
might be those flatworm kids again

 

[preef]

Fuge is on a reverse light cycle with chaeto. I'd hate to see the extent of the swings if the DT and fuge were on the same cycle.

 

[jbanks]

I would look at another cause.. Your PH swing is acceptable and you will witness that swing every change in season where yo uopen or close your windows. I have seen quite a swing in PH in my system with no ill effects. I would be concerned about your ALK.. If you're carbon dosing, then 8 is fine. If you're not, you should work on getiing that up to 11 or 12 dkh.

 

[preef]

My ALK has been dropping as my tank recovered. Indicates more ALK update which is good. I'm always afraid to up the dosage to quickly. I increased the dosage a few days ago. I'll test again soon.

 

[roiy]

what do you use for testing Alk ?

Tried crossing the results with different test kit ?

 

[preef]

I've checked with two Salifert kits. I cross checked them with the supplied reference samples.

 

[roiy]

I've checked with two Salifert kits. I cross checked them with the supplied reference samples.

Me and some other reefers from IL found the salifert test kit from different batch's taking up the result between 2 - 3.5 m/l Alk in compare to Tropic marine test kits.
I am not saying all Alk salifert test kits are bad just that i have found a lot of reefers from our community lately with the same problem cause.

If you could check with another company test kit (IMO best with T.M).

 

[jbanks]

I've had a pretty good experience with ELOS ALK test kit as well. Actually, it's time to order another one I use this kit the most!

 

[preef]

Me and some other reefers from IL found the salifert test kit from different batch's taking up the result between 2 - 3.5 m/l Alk in compare to Tropic marine test kits.

I've had a pretty good experience with ELOS ALK test kit as well. Actually, it's time to order another one I use this kit the most!

Thanks. I'll try a different test kit.