Help me understand Kh

[Jdavison911]

I purchased a Kh Guardian a couple months ago and have been able to keep a good eye on what’s going on with my alkalinity. So here’s my question my Kh swings up during the day and drops at night, why? I dose all my Alk after 6pm to try and make up for what’s falling but unable to do so. Here is what a couple days look like. The thing is if I select a time of day it’s pretty much the same reading day to day. Everything I see preaches on Kh stability. Is this unstable? Thanks everyone.

 

[LobsterOfJustice]

Alkalinity monitors are relatively new to the market so we are just starting to get insights into alkalinity swings throughout the day. Generally when people talk about swings they are talking about if you were to test the same time day to day.

I also have a KH Guardian and noticed that most of my alk consumption happens a few hours before to a few hours after lights out. Consumption drops to near zero from midnight to a few hours before lights on. Corals do not use the alkalinity consistently throughout the day. I think it is probably a worthwhile goal to adjust your dosing to try to minimize the drops since you have the information. The easiest way I found to do this was to set the auto-dose feature of the KHG to maintain the upper end of the swings, so as to fill in the valleys. I also shut off my main doser during the hours that I noticed all climbing due to no demand.

 

[Jdavison911]

Thanks for the reply. I will work on the dosing side of the valleys. I also failed to mention I have my apex set up to stop dosing ALK when Kh > 8.2 so I wonder if that is having an effect on it. I think that might be messing with my dosing more than I want it to because the guardian test every 4 hours and my dosing schedule is primarily during the night every couple hours so in fact this could be telling the doser to stay off when actually needed. I will remove the safety and monitor.

 

[chipmunkofdoom2]

This is not what reefers are referring to when they talk about alkalinity stability. Remember that until just a couple years ago, we had no way to monitor alkalinity with this precision, aside from manually testing alkalinity every hour by hand. Even now, devices such as these are still very uncommon in the hobby. Every other reefer who supplements carbonate alkalinity, whether through a two-part or using a calcium reactor, likely experiences the same swings that you're noticing. Without a real-time alkalinity tester, you wouldn't be able to tell. We seem to be growing corals as a hobby just fine despite the daily consumption changes.

When reefers refer to "alkalinity stability," they usually mean testing alkalinity and getting the same result time after time. If you are getting roughly the same alkalinity values at the same time every day, then your alkalinity is as stable as that of an aquarist that tests with conventional alkalinity test kits.