Alk not being used up in tank

MikeyB · Sep 16, 2014

Hey gang, odd question here. I got my 150 gal sps tank running, everything is looking good, sps grows albeit rather slowly but for some reason, i haven't had to dose any alk in almost a month now, even though im dosing around 25 ml of calcium a day, unless all that calcium is precipitating out. Hopefully someone can chime in and help me out here.

I was running biopellets for a while but turned them off 2 weeks ago as i was starving my tank

Here's a quick run down of everything.

Nitrate - 0
Phos - .8 (a bit higher then id like but slowly lowering it)
Alk 8.3 dkh
Calc - 420
Mag - 1380

Also running 250w mh/t5 lights.

ritter6788 · Sep 16, 2014

That is odd. Alk should be the first to decline.

You're not dosing anything else at all? What salt mix are you using?

mike007 · Sep 16, 2014

Maybe your salt mix is supplying the alk needs for your tank. You might want to double check your test results with another test kit. What are your alk. readings?

MikeyB · Sep 16, 2014

ritter6788 said:
That is odd. Alk should be the first to decline.

You're not dosing anything else at all?

Odd right? Im testing with a hanna reader, so i find it odd that it would be off. Only things im dosing are BRS calc, and a small amount of acropower every day

MikeyB · Sep 16, 2014

mike007 said:
Maybe your salt mix is supplying the alk needs for your tank. You might want to double check your test results with another test kit. What are your alk. readings?

It's instant ocean salt mix, and i havent done a water change in 2 weeks or so, just checked it before i posted and its still right where it has been

ritter6788 · Sep 16, 2014

MikeyB said:
It's instant ocean salt mix, and i havent done a water change in 2 weeks or so, just checked it before i posted and its still right where it has been

You likely are getting a drop in alk then. IO is higher on alk and lower in calcium. IO was 380 cal and 11 dkh the last batch I tested. You're probably actually increasing the cal by dosing and the alk is slowly declining by coral growth.

MikeyB · Sep 16, 2014

ritter6788 said:
You likely are getting a drop in alk then. IO is higher on alk and lower in calcium. IO was 380 cal and 11 dkh the last batch I tested. You're probably actually increasing the cal by dosing and the alk is slowly declining by coral growth.

Wow, could it really be that simple? I was going out of my mind here the last month wondering why ive had to dose so much calc, but not a single drop of Alk. That's a huge relief to me then. That being said, i appreciate the quick response from everyone, Thanks!!

ritter6788 · Sep 16, 2014

MikeyB said:
Wow, could it really be that simple? I was going out of my mind here the last month wondering why ive had to dose so much calc, but not a single drop of Alk. That's a huge relief to me then. That being said, i appreciate the quick response from everyone, Thanks!!

Test and get your numbers then don't dose or do water changes for a few days. Test everyday and see what is declining and how much.

MikeyB · Sep 16, 2014

ritter6788 said:
Test and get your numbers then don't dose or do water changes for a few days. Test everyday and see what is declining and how much.

Gotcha, im going to turn off my doser here, test calc real quick, write em down and i'll report back here in a few days. Thanks!

ritter6788 · Sep 16, 2014

Another thing you can do is bring the calcium up in your newly mixed salt water before doing water changes. Many people use IO and bump the calcium up a but before using. Just test early and often!

Good luck.

mike007 · Sep 16, 2014

Test your water and then quit dosing for 3 days and then retest divide results by 3 and that will tell you your daily consumption and then you will know how much you need to dose to keep parameters stable. I use the Brs reef calculator to determine how much to dose each day to maintain. Sounds to me that your salt mix is supplying the alk. demand for your tank.

MikeyB · Sep 16, 2014

Thanks for all the info guys! I'll post back here in a couple days with my new findings.

Randy Holmes-Farley · Sep 17, 2014

What do you use for top off?

Tap water can have a lot of alkalinity in it.

You are dosing nothing else for any reason? Some additives have alkalinity in them, even if that is not made clear to users.

Did you previously need to dose alkalinity, or is this a new tank?

MikeyB · Sep 17, 2014

Randy Holmes-Farley said:
What do you use for top off?

Tap water can have a lot of alkalinity in it.

You are dosing nothing else for any reason? Some additives have alkalinity in them, even if that is not made clear to users.

Did you previously need to dose alkalinity, or is this a new tank?

Hey randy thanks for chiming in.

I'm topping off with ro water from my Rodi unit so that's all good.

Other then acro power and Calc nothing else regularly. I did try a bottle of zeovit coral vitalizer but didn't notice anything different.

Tank has been up for almost 2 years now. Although I did upgrade tanks a year ago to a bigger one. Just moved everything over.

I guess you're the perfect guy to answer this question. Do bio pellets have any effects on growth of sps? Ever since I took mine offline all my coral seems to be doing much better.

I know how bio pellets work as I did plenty of research before I started and I know sps likes a small amount of nitrate and phos. Could the bio pellets of been starving them so much they just weren't happy and didn't grow that much?

Randy Holmes-Farley · Sep 17, 2014

FWIW, there is no way for calcium to decline and alkalinity to not decline, except by water change with a salt mix that has lower calcium than the aquarium.

It may just be that the demand is very low, and the water changes are lowering the calcium. IO is on the low side with calcium, so that may be it.

Pellets won't directly impact alkalinity long term, but depending on what happens to nitrate and phosphate, the growth of corals may be slower or faster, impacting the demand for calcium or alkalinity. If corals are starving, yes, that might reduce demand for both calcium and alkalinity.

MikeyB · Sep 17, 2014

Randy Holmes-Farley said:
FWIW, there is no way for calcium to decline and alkalinity to not decline, except by water change with a salt mix that has lower calcium than the aquarium.

It may just be that the demand is very low, and the water changes are lowering the calcium. IO is on the low side with calcium, so that may be it.

Pellets won't directly impact alkalinity long term, but depending on what happens to nitrate and phosphate, the growth of corals may be slower or faster, impacting the demand for calcium or alkalinity. If corals are starving, yes, that might reduce demand for both calcium and alkalinity.

That's great. Thanks for all the info. I think my issue was a combination of multiple things. Water changes with high alk, low demand combined with running pellets which probably lowered it even more.

I had an issue with phosphates a while ago and came to find out my rocks were full of phos and then continued to leach out when I was trying to lower them. I lost a bunch of pieces going through all that so now I have a bunch of frags which is probably why the demand is so low.

That being said. Thanks for the great info and help from everyone. I'm not going to dose anything for a couple days and see what the demand is for my tank and go from there

Randy Holmes-Farley · Sep 17, 2014

Sounds good.

Good luck.

Budman's Corals · Sep 19, 2014

ritter6788 said:
You likely are getting a drop in alk then. IO is higher on alk and lower in calcium. IO was 380 cal and 11 dkh the last batch I tested. You're probably actually increasing the cal by dosing and the alk is slowly declining by coral growth.

Do you have any idea what the Alk is in the Reef Crystals?