dry rock, dry sand, new tank.........where's my alkalinity going?

[reef tank 2.0]

i've had 5 fish (2 clowns, blenny, 2 cardinals) in my tank for about 5-6 weeks now. All is going well.
Added 3 coral frags 2 weeks ago - 3 head trumpet, 3 heads of zoa's, inch or so toadstool, and 3 headed stylophora. all small corals.

I have been testing my water weekly to get a feeling of where I'm at, and to see what parameters are lacking. there seems to be one that is consistently low.

I have been doing roughly 40 gallon water changes every 1-2 weeks. I use reef crystals
the parameters are pretty much the same when I test weekly.

the one parameter that is lacking is Alkalinity. For some reason it doesn't get higher than 6.9 (salifert test kit). I have also went as far as testing the fresh batch of saltwater in my storage bin. That reads 9.0, which is acceptable. On the low end, but at least it's in the accepted range.

I did start the tank up with dry rock and dry sand, not sure if that has anything to do with it. but doing 40-50 gallon water changes isn't raising that parameter.

I remember in my last tank, I was dosing like crazy. struggled to keep my levels up as well. I never had any issues with the tank, other than the level not being where I'd hoped it would be.

I find it hard to believe that a tank this new, small, and very few corals/fish in it.....would need me to be dosing at this point.
I get it, you need to dose when you need to dose..but this soon in the game?

any ideas?

salinity - 1.025
temp - 78
nitrates - 6.4
calcium - 440
phosphate - 0
magnesium - 1200
ph - 8.2
alkalinity - 6.9

 

[Randy Holmes-Farley]

Likely explanation is calcium carbonate precipitation onto all those existing and bare calcium carbonate surfaces which act as seed crystals for more precipitation.

Let alk stay there for a while.

 

[reef tank 2.0]

i'll be keeping an eye on the corals to see if they raise red flags due to the low parameter.
right now they all look happy, except for the trumpet, but I also think that's due to location (flow/light)

 

[Mr.Fishtank]

I was having the same thing happen when I set up my new tank. I didn't have any coral or coralline algae and the tank was consuming about .3 dkh per day. My tank has now been running for about a 18 months. I have lots of coralline and a few mini colony sps and the tank is consuming .2. It's pretty weird but not uncommon. It could be binding with the substate or live rock.

You said that your new salt mix test at 9 dkh. That is not low. I would say most people are keeping their alk between 8-9. I personally keep mine around 7.5 - 8.0 . I would also invest in a alk tester by Hanna . I have always had pretty accurate readings when I compare it to an ICP test.

 

[reef tank 2.0]

when I refer to the ideal reef tank parameters, it shows alk is best between 8-12dkh.
which is why I mentioned 9 being low

 

[Peair]

Try and keep all other parameters in range especially calcium, and then add an Alkalinity supplement, but be careful because your alkalinity could then spike high, easy do it and test.

 

[UMALUM]

I agree with Randy 100% adding that your trumpet is most likely upset with no phosphate in the system. The others will eventually follow unless you get your nutrients balanced.

 

[Randy Holmes-Farley]

when I refer to the ideal reef tank parameters, it shows alk is best between 8-12dkh.
which is why I mentioned 9 being low

I recommend 7-11 dKH and the ocean is below 7 dKH.

 

[UMALUM]

If your gonna rely on water changes for balance which is perfectly fine at this stage you might want to bring your salinity up. My last 3 buckets of rc mixed at 26 faired 10 / 440 / 1350.

 

[reef tank 2.0]

let me ask this...hoping to not waste money, should I wait a certain amount of time before adding more coral, due to my 0 phosphates/low alk?

 

[UMALUM]

let me ask this...hoping to not waste money, should I wait a certain amount of time before adding more coral, due to my 0 phosphates/low alk?

Yes!!!

 

[UMALUM]

Are you running a skimmer?

 

[reef tank 2.0]

Yes

 

[UMALUM]

Maybe shut it down till phosphate register?

 

[kenchilada]

I recommend 7-11 dKH and the ocean is below 7 dKH.

This. I shoot for 8.5-9dkh because it gives you a couple points of breathing room in either direction.

 

[niccumec]

Likely explanation is calcium carbonate precipitation onto all those existing and bare calcium carbonate surfaces which act as seed crystals for more precipitation.

Let alk stay there for a while.

@Randy Holmes-Farley - Would I be causing problems by dosing to keep Alk and PH up or just wasting my time?

Same low Alk here on new tank without corals (only two clowns and lots of pods).

I was planning on dosing with Recipe 1 (baked baking soda) to to maintain 8-9 dkh, which is also raising my pH to 8.2-8.3. If I just let it be, my Alk falls below 7 and my pH hangs around 7.8-7.9.

Also, my HW-Marinemix Reef salt is mixing up with low Alk (around 7), so I add baking soda to bring it up to ~9 dKh.

190 system vol | Marco Rock | Carribsea “live” sand | External w/ chaeto | LifeReef Skimmer | Pods