Low Alk 7.4, not typical

[jetskiwilly]

6 month old Redsea 130L...started with live live rock. I dose 20ml of kalkwasser every hour. typical alk is normally very steady at 8.5-9 dkh. Dose fluval mag cap full once a week.

PH 8 in the morning 8.3 at night
No 0.5
Po 0.03
Calc 430
Mag 1000-1100
Redsea pro salt


3 small sps frags, rest is full of bta, zoa, mushrooms.
The only thing I can think of is I have changed my water change schedule from 5 gallon every week to 5 gallon every 2-3 week since Dec 1st.

brain storming...I have been seeing white dots...maybe low mag is condensing(wrong word for it) calcium from water, and droping alk. But calcium isn't far out of range. I see calcium numbers from 450 to 525 depending on type of water I use in hanna checker.

 

[jetskiwilly]

Corals are happy, Zoa may be closed because I cleaned glass for picture.

 

[Shirak]

huh A lot to unpack here. What is your salinity? Your numbers are low which could indicate low salinity. The Red Sea Coral Pro salt should have much higher Ca/Mg/Alk at the 35ppt salinity than your tank indicates. Yes reducing water changes will affect your Alk in the tank as you are replacing less by increasing the time between water changes.

Your low Mg isn't combining with the Ca and precipitating. Maybe your Kalk dosing is causing some precipitation? Why are you dosing 20ml of Kalk an hour for 3 small sps frags?

Not sure what you mean by "I see calcium numbers from 450 to 525 depending on type of water I use in hanna checker." I don't use the Hanna calcium checker but they are very clear on what type of water to use for the dilution or your results will be wonky. So if you are not using the correct water how do you know what your tanks Ca is?

With only 3 small sps frags and what appears to be only soft coral for everything else. You shouldn't need to dose anything really to keep up with demand. Regular water changes each month should be more than plenty.

 

[jetskiwilly]

I thought I dose kalk for the same reason everyone else does....or so I thought....it elevates alk/carbonate and calcium and PH. Without kalk PH is ~7.6.

My calcium is typically +450. In the past I have accidentally used the different types of water in hanna checker. It calls for deionized waster and distilled water is ok per instuctions. Side note...one time accidentally filled the whole tube with reef water from tank, did test as instructed and resulted in same calc number after retesting with distilled water.

Low Mag....had to check my references and language. Magnesium is a buffer between calcium and carbonate. Low mag allows calcium and carbonate to combine quicker/easier and precipitates both out of the water.

My tank being mostly lps and softy I have excess calcium, I also run a lab28 calcium block. The carbonate/alk is either being used up or running lower due to precipitation. These are just my theory's, let me know what you think. Im going to try to correct mag...and do a water change in the short term. Long term may need to start looking into adding a 2 part to keep up with ALk.

Salinity....I havn't checked, will do it tonight, but I don't get a lot of salt creep and have an ato so I think thats a long shot, but we'll find out tonight.

 

[Shirak]

Yes Mg is a buffer to help prevent some precipitation of calcium carbonate. As well as minimize Ca from sticking to other things like rocks and sand. You could be losing some Alk if that is happening. With a few LPS and sps acro frags you are using up a little Alk there too. How large is your tank? I don't use Kalk so not sure if 20ml/hour is alot or not.

The reason I ask about the salinity is your Mg is quite low and it should be much higher with regular water changes and the salt you are using. Mg doesn't get used up very fast and I don't see a ton of coralline algae. Low salinity could also be a reason for lower Alk and again the salt you are using it should be fairly high even with some LPS and a few SPS frags IMO. As long as you have been doing regular water changes, which I think you have? What do you target for your salinity level and what are you using to measure when you mix up water? Will lose a little to salt creep and skimmer waste etc but if it is low it's more likely whatever you are using to measure it for water changes.

 

[jetskiwilly]

Tank is 34 gallons. Salinity was good...33 or 1.026. I use redsea pro, think its 9dkh, and 1350 mag. Use a refractometer. Just hit the tank with some Reef Fusion2, 5ml of akl, should have tested it before, before dosed, now alk is at 8.5.

 

[kagisexton]

7.4 is not low, if anything it's ideal

 

[Shirak]

7.4 is not low, if anything it's ideal

7.4? what are you talking about?

 

[Shirak]

Tank is 34 gallons. Salinity was good...33 or 1.026. I use redsea pro, think its 9dkh, and 1350 mag. Use a refractometer. Just hit the tank with some Reef Fusion2, 5ml of akl, should have tested it before, before dosed, now alk is at 8.5.

1.026 should be 35ppt so which are you reading? Red Sea coral Pro black bucket or Red Sea blue bucket?

What are you using to calibrate your refractometer?

 

[LeftyReefer]

I think your salinity is probably low. 33pt is not 1.026.

 

[TheDragonsReef]

I keep all my tanks around 7.5 dkh. Its where most natural reefs sit.

 

[Spare time]

Ph at 7.6 (without your dosing) sounds strange. What do you use to test it?

 

[Shirak]

I keep all my tanks around 7.5 dkh. Its where most natural reefs sit.

huh? ok... but the OP isn't running 7.5dkh

His pH is 7.6

 

[TheDragonsReef]

huh? ok... but the OP isn't running 7.5dkh

His pH is 7.6

The title of this post is "low alk 7.4, not typical" then he talks about an alk issue throughout the first post. Later he says his ph drops to 7.6 without kalk. So im assuming hes still continously dosing kalk and still having low alkalinity.

And op, your lps if growing fast can take up lots of alk as well.

 

[Shirak]

The title of this post is "low alk 7.4, not typical" then he talks about an alk issue throughout the first post. Later he says his ph drops to 7.6 without kalk. So im assuming hes still continously dosing kalk and still having low alkalinity.

And op, your lps if growing fast can take up lots of alk as well.

Yeah I dunno... says his alk is usually around 9 So I guess what he means it is not typical for him.

Something confusing going on that I don't attribute to a few lps and acro frags.

 

[Randy Holmes-Farley]

If the water volume is 130 L, he kalkwasser being added is quite low, only adding 0.2 dKH per day.

It may meet the needs in some tanks, but it is not surprising that alk may eventually begin to drop as organisms use more.

Where exactly are the white dots? It may be coralline beginning to grow, which uses a lot of alk.