BigJohnny
2500 Club Member
Just FYI after using my alk monitor for a while now I've noticed my tank consumes almost 75% of the daily total during lights on and almost 50% during peak par, with most of that occurring in the 2nd half of the peak. I now dose balling accordingly and my alk has never been more stable. It's not just me either, many people have observed the same thing. Obviously this is primarily due to peak photosynthesis but also due to higher pH during lights on and therefore increased calcification rates and precipitation.Sorry for the lack of updates, let's get caught up.
I've been trying to get the tank to settle down after the disastrous carbon dosing experiment.
The Lokani went through another round of RTN and stopped again. It's in back under lower light now and in the process I made two frags. One died, one lived, so now I'm at 2 frags plus what remains of the original colony.
My KH reached 7.0 a few days ago and I was happy I finally managed 7 ... a few days later it started to bother me since this tank hasn't hit 7 for months so I tested again, 9.1 KH! BAH! Doser turned off, Kalk diluted the first day, then resumed at full strength once I confirmed Alk was dropping at a decent rate. Since then I've bee obsessed with day vs night Alk usage so I'm doing multiple tests daily to try and figure out current daily usage plus day vs night usage. My concern is that with the Alk usage rising I'm actually becoming more unstable by dosing 24/7 rather than just during the daylight hours. THis is a meaningless fact in younger tanks but as coral volume increases and daily dosing increases these swings can become a real issue.
For the sake of discussion, lets say my daily Alk usage is 2 KH. If I dose that over 24 hours then my morning Alk will be 8, end of light cycle will be 7, and then it will climb to 8 by the next morning if we assume corals do not use any Alk at night (which is what many are confirming). This assumes I'm dosing enough for 1 KH during the 12 hour day and another 1 KH overnight so the drop is only half of the total daily usage.
Maybe 1 KH is no big deal, but what if My Alk usage is something crazy, like 6 KH daily?
Suddenly I'm doing daily swings from 9KH in the morning to 6KH in the evening. That's pretty flipping huge! As you can see, continuing 24 hour dosing and continuing to raise the amount as the tank grows actually decreases stability due to the difference in day/night usage.
That's my theory. I don't have an expensive 24/7 Alk tester but I am doing numerous tests here for the next day to see if I see the pattern. Because my KH spiked to 9 my doser is off but Kalk is still being added via my timed topoff every 15 minutes. It's saturated Kalk so using the calculator and figuring my usage is about .8 gallons daily, this equates to 0.6KH of Kalk added daily.
So far my daily measurements with Salifert, backed up by Hanna, are:
9.3 at 4pm
8.8 at 6:30pm
8.6 at 8:30pm
8.5 at 6AM (Kalk back to full strength, my estimate is + .3 to .4 KH overnight)
8.1 at 4PM
7.9 at 6:30PM
7.7 at 8:30PM
8.0 at 6:30AM
I expected Alk to rise due to Kalk dosing and it did. I expected up to .3 and testing twice I got 8.0 twice so I think this is a decent reading. There should have been some usage after the 8:30 reading due to the blue LEDs being on full blast until 9:30. Most likely I am dosing more Kalk than I thought, which is likely since it's a guess based on how long topoff lasts. 5 gallons last a little over 5 days. Remember I do timed topoff with Kalk, it's not float based, so dosing is consistent.
So, if all goes as expected this evenings Alk should be 7.2 KH, tomorrow morning 7.5, tomorrow evening 6.7 if I don't turn on the doser.
Running the calculator and getting the amount to raise Alk from 6.7 to 7.5 I get aprox 80ml (I'm using 140 gallons as tank volume + sump - equipment and rocks).
Doser is set to 120ml over 24 hours so what I think I will do is put it on a timer so it goes on Saturday at 10am and off at 10pm. This should dose 60ml which is not enough to fully maintain Alk. A safe start. If this works then in the end I will have more stable Alk by only dosing during lights on.
Of course this assumes that the Alk spike was short and not too damaging. Right now everything looks good but Alk spikes can show damage days or weeks later so we'll see.
What's left of the Lokani
After latest rescape and slight trim. I wanted to get more light in front to safe some dying/shaded corals. Big white coral in the middle back is the skeleton of my Purple Stylo from my first crash over a year ago. Makes a good temporary fragish rack. My wife, who is NOT into reefing, saved it for me after finding it in my death bucket and washing it off.
Primary Alk consumer
Blue LED fun.
Pink Milli left, Palmer's Blue right, Big Valida below. To my eye pink glows pink, Palmers same, polyps of valida are invisible.
I have a very young tank with only frags and mini colonies which only consume 1 dKH per day, I'd imagine a more mature tank would see an even larger percentage difference as calcification needs increased while daily precipitation remained relatively consistent. I don't have any visible precipitation or anything like that but it's always occurring in one way or another in all of our tanks, as I am sure you are aware.
Last edited:
