Neptune Dos goes crazy or did I do it ?

cobraz · May 30, 2026

So, I had my 2 part in my Dos running with a DDR.everything has been running per settings (i.e. I set Alk at 20ml with in a 0 to 23:50 time period.
Worked fine....
I then decided to set the parms at 8.4 with a .20 range +/- and a 10% limit. I set it to table.
The Alk creeped up to 8.87. Which I thought it would stay between 8.2 to 8.6 plus 10% which would top off at 8.74 max..I am I not understanding the values ?
Then this morning I changed it to just "on".
Here where it gets crazy...it dumped 200ml at 6:30am another 200ml at 7:00am and another 200ml at 7:30..I caught it when I work up and turned the power off...
I have done a 10 gallon water change and Alks down to 10.39. Going to do another later tonight.

Can anybody explain what happened and why ?

cobraz · Jun 1, 2026

Follow up:

Well, despite the blow up...3 water changes of 10 gallons each...lowered the numbers to safe levels within 24 hours.

No losses, everybody's good including the coral. Went on Neptunes site and Youtube and adjusted my dosing parms. Pulled out one piece of equipment and added a second Dos and DDR.

Now Alk, Cal and Mag is controlled with limits and Strontium is just 1ml a day...manual testing to see where it holds.