Trying to achieve stability

[winemanta]

I’m getting some swings with my pH , CA, MG and dkh. I’m hoping someone may be able to educate me…

Equipment:
Reefer 525xl - running with fish for 15 months
Reefmat
Reef Octopus 150INT skimmer
BRS mini reactor Carbon ROX (runs 3-4 hours per day)
Apex Controller
Apex DOS (NOT currently run by Trident)
Apex Trident
CO2 scrubber with BRS media (changed every 2 weeks - pH runs a low 7 without it
Refugium running for about 10 months - algaebarn pom pom macro growing well

Stocked with Tangs (Naso, Blue, Sailfin, Convict, Chromis (Black Axil, Green, Blue), Blenny, Engineer Gobies, Cardinalfish, Fairy Wrasse. (Tangs are less than 8” and I’m in the process of setting up another tank for the Naso - all were introduced to the tank as juveniles and get along well - Naso and Blue share their cave).

Corals - mostly soft corals - Zoas, Ricordias, leathers, mushrooms. Some LPS - gonioporas, hammer. Rock flower anemones.

Everyone is happy and doing well. Frags aren’t growing as quickly as I would like, but they are opening up and appear healthy.

Chemistry:
pH swings from 7.7 to 8.1
Ammonia : 00
Nitrites: 0
Nitrates : around 40 (higher than I like, but expected given the livestock)

Salt mix is Tropic Marin Pro with RODI mixed 24 hours prior to water change with circulation at room temp (which is about 2-3 degrees lower than the tank temp).

I attached a picture showing my swings following a water change. Before the water change my dkh and ca were set at 0.5ml per day - only dosing to keep the line operational. I do a water change (15 percent) about once every 3-4 weeks and struggle with keeping the parameters stable as a result of the water change. It can take 2-3 days for it to come up a little on its own, then I dose slowly to raise it to normal, enjoy a stable tank for about 2 weeks, then have to start all over again with the water change.

Anyone have suggestions?

 

[Reefer Matt]

If your current salt mix has lower alk, ca, and mg than you want to normally want to run at, I suggest changing the salt mix, or possibly getting a Neptune DŌS, and doing a constant water change every day of a couple gallons or so to minimize the swing.

 

[Randy Holmes-Farley]

I only see a "swing" in pH, which is normal, although if yours is accurate, the low pH end may be a concern.

Alk and calcium will decline, and most often needs to be dosed to keep them up.

I'm sure you have no real magnesium decline in your system if not adding large amounts of alk and calcium. I suspect the low value is either low salinity (what is your salinity?) , or test error (very common).

 

[winemanta]

Salinity is 33 ppt. My pH and my alkalinity seem to disturb my lps. I haven’t lost any, but they don’t like it when that changes too much. My pH was maintaining around 8.1 for a week or more, then drops. Co2 scrubber helps, but only a little. I feel like I am constantly chasing it after doing a water change.

I know my swings are small right now. I don’t want to make it worse by switching to the wrong salt and swinging high. Swinging low and dosing is better than too high. I’m open to a different salt, but I think it should have a kh around 9 max if I do that.

Thoughts?

 

[Randy Holmes-Farley]

If you raise the salinity to the ocean average of 35 ppt, magnesium will be above 1290 ppm, which above the normal ocean average value (1280 ppm) and will be fine.

If the pH is accurate, fresher air to the room is one of many ways to raise pH.

Just to be clear, you are not dosing anything to this tank?

 

[winemanta]

Once I do a water change I’m dosing for about a week part a and part b (Red Sea). That’s the chase. After a week, I can decrease the dosing gradually down to 0.5ml per day of each. That isn’t doing anything but keep the line moving. My tank will then be stable for 2 weeks and it’s time for another water change and the cycle starts all over again.

 

[Randy Holmes-Farley]

What is the alk of your new salt water compared to the tank alk? Any alk between 7 and 11 dKH is fine, as long as it is not high alk, low N and P (which can lead to burnt tips on some SPS). Just try to keep it stable.

You can adjust the alk in new salt water if you want.

 

[Dennis Cartier]

Once I do a water change I’m dosing for about a week part a and part b (Red Sea). That’s the chase. After a week, I can decrease the dosing gradually down to 0.5ml per day of each. That isn’t doing anything but keep the line moving. My tank will then be stable for 2 weeks and it’s time for another water change and the cycle starts all over again.

It sounds like you are dosing to try to deal with a shift in parameters after a water change? That is a bit like the tail wagging the dog. Normally you dose a steady amount daily as a baseline to replace the elements consumed daily. This keeps the macro elements steady and prevents swings.

In your case, as Randy mentioned, you may want to move to 35 ppt salinity, which will raise all your macros across the board, and just try to do your water changes with new water with a matching salinity (35 ppt), and with parameters that match your preferred range.

So the point is, doing a water change should not cause a need to alter your dosing.

You can even do a water change with different parameters, just be sure to do it slowly spread across days rather than all at once. However salinity should always match.