Multiple Params Fluctuating

Spacemonkey · Jan 27, 2023

Hi all, Firstly very happy to be a part of this community, I've been browsing the info on here to get me started over the last few weeks and am just trying to get things to settle before I add first fish etc..

I'm not entirely new to fish-keeping, I've had tropical most of my life and dabbled with marine for just over a year (successfully) about 8 years ago. I've recently got back into the hobby and am having a few issues I'm hoping you can assist with:

To give some background I have a Fluval flex 123L or 32.5 Gal with a SSB made of Coral sand, I have approx 15kg of Live rock and am currently running filtration comprised of Filter wool Carbon and Fluval Biomax with a fluval ps1 protein skimmer. The tank has been running a week and a half and I have done a 25% water change already (as PH was a tad low) I'm using RO water with TDS 0, and Red Sea Coral Pro Salt.

My issues with parameters are:

PH stays at 7.6 or below (Salt says should be 8.2-8.5, which it was before I added it to the tank)
DKH Was 10.5 on the 24th and is now 7
Calcium was approx 400 When I first tested a few days ago, this is now beneath the scale, going by the measurements on the scale it's probably around 150mgl
Magnesium stayed the same at 1400mgl

Nitrite, Nitrate and Ammonia all 0 now, they were low when I first tested last week.
Salinity Stable at 1.025

Now as far as I'm aware, there's nothing in my tank that should drop the Alkalinity or calcium so why are they fluctuating so much? I have a few hitchhiked corals on the live rock but its literally just a few zoa heads and some corralline, nothing significant. This is baffling me as I've not had the issue before, I'm hoping with a few water changes over the coming week it will normalise but any ideas you can throw in would be appreciated.

Thanks for taking the time to read.

KrisReef · Jan 28, 2023

Sounds like you also may have some dry rock that is pulling minerals from the water column? Otherwise, its a mystery.

Big G · Jan 28, 2023

Did you cure the live rock before placing it into the tank?

Spacemonkey · Jan 28, 2023

Thanks for the quick responses guys, much appreciated.

So the first 10kg I got was ‘live rock’ but looked like dry rock in a vat with a few pieces of good live rock (clearly covered in the good stuff) then the next 5kg I got was heavily covered in good stuff. If the dryer rock is taking those nutrients in will it eventually stop?

Reading another thread on here about cycling and alkalinity spikes last night I did some thinking. I do remember a buildup of white powder/film on the heater the other day, I just thought this was residue from sand settling but could have been calcium dumping when the alkalinity rose?
Now that everything has calmed down I imagine this is causing the lower alkalinity and calcium?

KrisReef · Jan 28, 2023

Sounds like two good possibilities for the missing salts!

It will be interesting to see how much time will pass until the tank stabilizes. I hope it goes there quickly.

Spacemonkey · Jan 28, 2023

Thank you I will keep you updated as I do water changes and will hold off adding livestock till it stabilises.

Spacemonkey · Feb 1, 2023

Hi All,

Thanks for your help, an update as to what was causing the issue...

I decided to do a new batch of saltwater mix and just as it was ready I tested all params.

PH bang on
KH Bang on
Calcium again 150 ish
Magnesium Bang on

I continued with the water change anyway and suspected the test may be faulty. I tried 3 more calcium tests, all producing low results. My brother brought over his Salifert test kit which showed the calcium is Bang on too. So after all this, I believe two things happened:

1 The 'dry-er' live rock caused some instability and possibly a calcium dump (as KH fluctuated so drastically over the few days), this seems to have rectified now (and PH has stabilised at 8.4).

2 The Calcium test kit was throwing me off, I guess I'll never really know what it was while the KH fluctuated but all has stabilised either way and is now good to add my first livestock.

Once things are settled I'll add some pics in the relevant threads.

Thanks again for helping.

Spacemonkey · Feb 4, 2023

HI all, I'm back again, it seems that whatever is causing the issue is still at large. I don't think anything in my tank is enough to drop the alkalinity in a few days.. It's literally a small rock approx 5 inches by 4 inches covered in corralline and 7 zoa heads..

KH is down from 11 to 6 again, and the PH has gone down from 8.4 to 7.6 or less (Off the Red Sea scale). Im getting some Red Sea KH foundation to help stabilise and will let you know how I get on... Hopefully there's not a KH black hole in my tank.

Spacemonkey · Feb 13, 2023

FINALLY!

Apologies for the delay, these things take time.. I've got everything stable and steady now. It was dropping 1-1.5KH a day! Either Rocks, Diatoms, Corals or a combination of all three.. Either way I've sussed it.

KH I need to dose 10ml a day (Red Sea KH Foundation B) to keep the KH stable. The PH then stabilised.

And now slowly but surely I'm seeing usage of small amounts of Calcium and Magnesium as expected with Corraline and a few corals, they are starting to look healthier by the day and have grown fairly fast considering it's only been a few weeks.

I know there may be a point when the KH comsumption changes and will keep testing almost daily for this. For now though it's happy reefing for me. Looking forward to helping others and learn more as I go.