One time correction or time to start dosing?

[Fishy Guy]

My first reef tank (IM 25g lagoon) has been setup for about 6 weeks now and have a question about parameters and dosing. I am using regular IO salt and my Ca measurements have been consistently low; I'm trying to make sure the salt is mixed in the bucket thoroughly before mixing a new batch but I'm still only testing at about 380 in a fresh 5g batch. Since adding a few corals I've noticed my Alk is now beginning to drop as well. As of now I am just completing a weekly 5g water change.

	20-Jan-24	14-Jan-24	6-Jan-24	31-Dec-23
SG	1.026	1.027	1.026	1.026
NO3	20.1	18.2	11.5	8.7
PO4	0.26	0.15	0.15	0.07
KH	7.5	8.0	8.3	8.3
Ca	340	340	360	360

As I am still lightly stocked I'm hesitant to begin dosing if I don't need to but also want to be proactive and not wait until I'm having problems to address it. Should I do a one time correction or should I start to think about dosing? Or just continue with what I'm doing for now? Thanks.

Corals:

• Duncan
• Maze Brain
• Monti Cap
• various zoas
• Devils Hand Leather
• GSP

FTS; please ignore the crooked light ha

 

[Randy Holmes-Farley]

The alk does not seem to be changing much, so I'd just bring up the calcium (assuming it is accurate). It probably reflects whatever is in your salt mix at that salinity, but I'd test it too.

Regardless, even if it is actually 420 ppm, adding 60 ppm is not a problem.

 

[Fishy Guy]

The alk does not seem to be changing much, so I'd just bring up the calcium (assuming it is accurate). It probably reflects whatever is in your salt mix at that salinity, but I'd test it too.

Regardless, even if it is actually 420 ppm, adding 60 ppm is not a problem.

Thanks Randy!

Being new to the hobby what do you recommend for the adjustment? Just the calcium portion of 2-part system?

Also, I don't test mag but have seen the guidance to add 10% of whatever calcium you're dosing; would this apply here?

 

[Randy Holmes-Farley]

Thanks Randy!

Being new to the hobby what do you recommend for the adjustment? Just the calcium portion of 2-part system?

Also, I don't test mag but have seen the guidance to add 10% of whatever calcium you're dosing; would this apply here?

If you have a to part, just the calcium part is a good choice. Or you can get commercial or DIY calcium chloride.

I would not dose magnesium here since the calcium is not low by consumption (alk would drop 2.8 dKH for each 18-20 ppm of calcium, had it been reduced by consumption). If you use a two part with mag already in the calcium half, that's fine.

 

[Fishy Guy]

The alk does not seem to be changing much, so I'd just bring up the calcium (assuming it is accurate). It probably reflects whatever is in your salt mix at that salinity, but I'd test it too.

Regardless, even if it is actually 420 ppm, adding 60 ppm is not a problem.

@Randy Holmes-Farley I just tested again and am confused why my Alk seems to be slightly dropping with Ca remaining steady?

Alk has gone from 8.0 to 7.5 to 6.7 over the last two weeks with Ca holding steady at 340. This is with no dosing of any kind and just a weekly 20-25% water change.

I've got ESV B-Ionic two-part; before testing today plan was just to dose to bring up Ca to around 420. I'm going to follow the BRS calculator and do 1/3 of suggested dose each day over 3 days.

I'm wondering if I need to dose the Alk portion now too? Ideally I'd want to be around 8-8.5 dKH.

	27-Jan-24	20-Jan-24
SG	1.026	1.026
NO3	21.7	20.1
PO4	0.30	0.26
KH	6.7	7.5
Ca	340	340

 

[Randy Holmes-Farley]

An alk drop of 0.8 dKH would be accompanied by a calcium drop of 5 ppm, which kits are not going to accurately detect.

If you want alk higher, you'll need to dose soje of it too, but not nearly as much as the calcium part.

 

[Fishy Guy]

An alk drop of 0.8 dKH would be accompanied by a calcium drop of 5 ppm, which kits are not going to accurately detect.

If you want alk higher, you'll need to dose soje of it too, but not nearly as much as the calcium part.

I dosed the ESV B-Ionic over the last several days and have Ca reading at 420 now.

For Alk I did a single dose to bring it up from 7.3 to 8.3 per the BRS calculator. I didn't split the dose up like I did for Ca as suggested amount was only about double what the recommended daily starting dose would be whereas the Ca was like 20x the amount.

I did get an odd Alk reading of 8.9 on the 28th but I'm wondering if that wasn't just a testing error of some kind. Otherwise it would appear the tank is consuming 0.3dKH per day; does that sound reasonable to you?

	Jan-27	Jan-28	Jan-29	Jan-30
ESV Alk dose	10ml
ESV Ca dose	30ml	30ml	30ml
Alk	7.3	8.9	8.0	7.7
Ca	340	375	395	420

My question now would be is it okay to just do a small weekly correction dose as needed following water changes or should I do a daily maintenance dose of the ESV or AFR to keep it more stable?

Thanks again for your help @Randy Holmes-Farley!

 

[exnisstech]

It seems like you know how to calculate consumption so I would find a calculator to see how much is needed to maintain the level and dose that amount daily vs weekly. If your consumption is low weekly may work but I world prefer small daily dosing just for more stability. I have only used esv 2 part so I can't comment on other products. I manually dosed for years every morning, pour alk in the overflow and calcium in the DT and out the door to work. I eventually moved to dosers as consumption increased but would not bother early on.