Tank values crashing repeatedly

[Reedc200177]

I'm not sure if "crashing" is truly the right word, but my alkalinity seems to drop dramatically over a 24 hr period while my calcium and magnesium decline as well, but not as quickly or dramatically.

I've been using the 2 part calcium and alkalinity buffer, but I struggle to break 8 dkh, and if I do it's a day or so before it's trying to fall below 7.

I was ok with just daily dosing but I recently took a short 2.5 day trip, just before leaving did a water change and dosed, dkh was 8, CA 420, magnesium 1300. Came back to a few unhappy corals and a dkh of 6.4, CA 400, mag 1180. I realize I need to try to address the root issue but not sure what it is or how to fix it.

The tank is 4 months old. The only corals in it are a few "wild" sps that came in on the liverock order, which I know is not ideal for such a young tank, but up until this trip were doing great and actually growing and repairing damage from shipping. One coral that rode in is a large piece of oculina robusta. Other livestock are a few rockflower anemones, porcelain crabs, and 2 small ocellaris clowns. I cycled the tank for 2 months before adding livestock and rock, no ammonia or nitrate.

13.5 gallon fluval evo
Bioballs, floss, and carbon pad in filter
Using red sea blue bucket salt
RODI water 0 tds
Weekly 3 to 4 gallon water change
Dkh 8, but falls rapidly to 7 or lower without daily dosing
CA 420 to 430 typically but will fall
Magnesium try to maintain around 1300 to 1350
Nitrates 5 to 10ppm
Phosphates 0.03
Ph 8.4
Sg 1025

Using salifert test kits for all. I know the fluctuations are not good, not sure how to stabilize the tank though.

 

[IslandLifeReef]

I'm not sure if "crashing" is truly the right word, but my alkalinity seems to drop dramatically over a 24 hr period while my calcium and magnesium decline as well, but not as quickly or dramatically.

I've been using the 2 part calcium and alkalinity buffer, but I struggle to break 8 dkh, and if I do it's a day or so before it's trying to fall below 7.

I was ok with just daily dosing but I recently took a short 2.5 day trip, just before leaving did a water change and dosed, dkh was 8, CA 420, magnesium 1300. Came back to a few unhappy corals and a dkh of 6.4, CA 400, mag 1180. I realize I need to try to address the root issue but not sure what it is or how to fix it.

The tank is 4 months old. The only corals in it are a few "wild" sps that came in on the liverock order, which I know is not ideal for such a young tank, but up until this trip were doing great and actually growing and repairing damage from shipping. One coral that rode in is a large piece of oculina robusta. Other livestock are a few rockflower anemones, porcelain crabs, and 2 small ocellaris clowns. I cycled the tank for 2 months before adding livestock and rock, no ammonia or nitrate.

13.5 gallon fluval evo
Bioballs, floss, and carbon pad in filter
Using red sea blue bucket salt
RODI water 0 tds
Weekly 3 to 4 gallon water change
Dkh 8, but falls rapidly to 7 or lower without daily dosing
CA 420 to 430 typically but will fall
Magnesium try to maintain around 1300 to 1350
Nitrates 5 to 10ppm
Phosphates 0.03
Ph 8.4
Sg 1025

Using salifert test kits for all. I know the fluctuations are not good, not sure how to stabilize the tank though.

I believe that the blue bucket salt mixes to 8 dKh at 35ppt which equates to a little over 1.026. If you are changing 25-30% of the water every week, you are probable lowering your Alk below 8 dKh just with water changes.

A smaller tank seems to be harder to keep stable because a change in just a few gallons of water can make a bigger change in the tank. LPS and SPS will both use Alk.

 

[Reedc200177]

Well you are absolutely right, mixes to 8dkh. Don't know why I didn't think to check that. Would switching to a different salt be better then?

 

[thewedge]

Sounds to me like you have daily alk demand and need to maintain it via dosing either manually or with pumps. If you came back after not dosing for a couple days and alk decreased, that's expected. Particularly if you have sps. It means the coral are growing.

 

[Randy Holmes-Farley Verified Community Expert]

The magnesium is NOT changing detectably day to day. Those changes are test error.

An alk decline of 1-2 dKH per day is not unusual, and the balanced calcium decline is only 7-14 ppm per day.

 

[IslandLifeReef]

Well you are absolutely right, mixes to 8dkh. Don't know why I didn't think to check that. Would switching to a different salt be better then?

Not necessarily. Keeping your Alk around 7-8 is fine. I would recommend it. Just keep dosing and consider raising you salinity to 35 ppt.