Over-corrected Alk... again! Growth spike... burnt tips! Again!

[FishTruck]

I'll start with the punch line. My tank has chronically low nutrients (Nitrate and Phos are always zero). SPS, Fish, and Clams seem to do fine... so long as I keep my Alk at 7 or 8. Not higher! I learned this from trial and error - but never really understood it - until now. Here is my revelation. Play by play.

1. I came home from a short trip two weeks ago to find the CO2 feed to my calcium reactor was shut off. The solenoid just closes sometimes. *** Mistake ONE. Procrastinating getting a new CO2 regulator.. or.... an pH alarm that will tell me when the pH goes up in my reactor. This is an issue for three years that I just can't get excited about spending 300 - 600 dollars on.

2. I check the tank Alk - 5 dKH. Crap! An quick inspection reveals that the corals look fine. **** mistake number TWO. A dKH of 5 is very low in my tank. I should have double checked this. I just assumed it was right since the reactor was off. It was probably not that low.

3. So... I added two-part, to correct the Alk over two days and reboot the reactor. Target dKH is 7 in my tank. *** mistake number THREE - I did not keep checking the Alk. I just used my normal recipe for correcting alk 1 dKH per 24 hours.

4. Next thing I know, the dKH is 10. I notice that my green slimers have all grown cute little white "horns". Probably, about 50 "horns" when I counted them. Hmmmm. I decided to just sit on it. BUSY and all - and I want to see if my reactor is set right for stability. Alk stays stable at 10. That's good, reactor is set correctly. *** mistake number FOUR. I know from experience that my tank does better when my dKH reads 7. I should have shut it down and let it drift back down. Stubborn lazy idiot. And... I wanted to see what would happen. This tank is getting scrapped in about 8 months anyway when I move.

5. Next, these little "horns" get even longer.... but don't seem to be getting covered in flesh, some are turning brown (diatoms getting on them). I know I must intervene or take a ride on the RTN roller coaster. But... I also have a revelation.

I have read about burnt tips with carbon dosing and high Alk. I finally get it!!!

This is the classic explosive skeletal growth - without enough nutrients to cover it up with flesh. Check the "horns" on this little slimer. They appeared in a DAY. I swear... they were blunt ended before the Alk spike.

 

[Rick.45cal]

Simple solution to your problem would be to keep NO3 and PO4 in detectable levels.

 

[Rick.45cal]

You could dose NO3 and PO4 and stop the event.

 

[FishTruck]

Working on the NO3 and PO4. So far....

1. I got rid of my algae refugium
2. doubled the output from my automatic feeders
3. I have a bit of a bubble algae "phase" going on right now - it seems to be on the way out - but I am hesitant to step up the nutrients until it is over. Currently, shopping for a nice magnificent foxface, and maybe a couple other possible herbivores to help push the nutrient level while grooming the algae.

 

[FishTruck]

Just an update -

it turns out that my Alk test kit was faulty. My Alk was reading 4 dKH lower than reference. So, when I was measuring 7... the ALK was actually 11 (comparing my kit to and ICP reference lab). I got a new test kit for home use and verified the error.

So, in retrospect, my Alk swings were worse than I thought (from 9 - to probably 14 or 15), then, has been hovering at 11 or 12 since then - when my goal was to keep it at 7 or 8 dKH. In the meantime - I have raised my Nitrates to 10 ppm by aggressive feeding. Fish are happy - but my problem had less to do with low Nitrates and more with poor Alkalinity control. Bubble algae is becoming a problem... but that's another story.

Unfortunately, I lost all of my green slimers and a bunch of SPS frags. I just shut off the Ca reactor to let the Alk slowly drift down to 8dKH - where things usually work best in my tank.