pH up to 8.65 by lights out, problems ahead?

[slojmn1]

I recently started dosing kalkwasser with my NURCE top off unit. I was havng low pH during night time from 7.7 night to 8.2 by lights out during the day. Now 2 weeks into kalk as my top off I am finding dramatic swings in pH, from 8.1-8.2 at night(this is better night readings) to 8.65 :eek1: by lights out. This morning I found my pH at 7.9 and it hit 8.64 by lights out. I feel this swing could be a problem if it keeps up. I noticed three of my crocea clams who were previously fine pulling in a part of their mantles today. I am wondering if the pH swing is starting to bother them. Everyone else looks fine. Other parameters include calcium 440ppm, alk dropped from 10.9dKH last week to 9.3dKH today. I expected a lower number on the alk since my pH was up so much. That surprised me. I am considering cutting the kalkwasser dosing in half on the next go around and see if a more diluted mixture will work better. I have my refugium lights coming on around 4:00AM and off at 1:00 PM, MH come on at 6:30AM and off at 2:30PM, VHO lights on at 9:00AM and off at 8:00PM. Staggering the lights for heat purposes during the summer. I think I will get the refugium lights back on during the night and off by day. I did this for a while and saw no change in my pH during the night with the reverse cycle. Now my macro algaes are growing fairly well in the refugium so it may make a difference.

So a long winded way to ask if pH of 8.65 is detrimental in the long run? Is my pH swing problematic in the long run? and what do you think about my plan?

[ July 16, 2001: Message edited by: slojmn1 ]

 

[jdeets]

According to Daniel Knop, 8.3 is about as high a pH as a Tridacnid will tolerate. So the high pH is most likely affecting your Crocea adversely. The instability will also be detrimental.

You might try calibrating your pH monitor to make sure it's working right. I thought my pH was at 8.6 and a calibration of my monitor showed that it was really around 8.1. It had gradually drifted out of adjustment.

Try dosing the kalk ONLY at night. This will add some stability to your pH and keep you from having such wild swings.

 

[slojmn1]

jdeets, Thanks for the reply. I just calibrated my pH monitor about 8 days ago and it was barely out, maybe .02. I am using the NURCE top off system which doses small amounts of top off water whenever the level falls below the lines. This happens randomly throughout the day and night. Due to higher evaporation rates during the day with fans running I suspect the top off runs into the sump more during the day. This makes dosing just at night impossible. I ran my refugium lights during the night last night and my pH only dropped to 8.2, it has since risen to 8.4 a third of a way through the light cycle. Sounds like I may have to rethink the NURCE unit with kalkwasser. I thought about diluting the next batch quite a bit so smaller amounts of kalk are going into the system with the top off. One of the clams looks back to normal this morning, the other two still look off, and the smallest continues to decline. I think I may lose him. The two t max's appear totally unaffected at all, just the croceas are showing signs of being unhappy. The smallest one was fine until I moved it, so its decline could be also related to the movement along with the high pH and pH swing in general.

 

[reefworm]

slojmn1,
Good advice from jdeets. In addition to his suggestion you can also add white vinegar to your kalk mix, about 10ml per gallon or so. Not only will the vinegar lower the pH slightly, it will also provide additional free carbon to which your calcium can bind to form the calcium bicarbonate your corals need. HTH

regards,
rw

 

[slojmn1]

reefworm, Thanks for the idea of the white vinegar. I will do that in the next batch. Unfortunately one of my croceas continue to decline, the small t max is also on the decline. The other two croceas that seem affected are about the same. My pH has been lower since I diluted my kalk yesterday. Hopefully this will help my clams.