Ca & Alk refuse to increase despite +300-400% increases in daily dosages

[Spencer]

Hey Randy et al.,

Here's the problem I'm having with my ~2 year old Red Sea 170 acro tank...

Growth was looking OK back in July after a successful move (June 29th) but it has always been suspiciously/painfully slow. I noticed things we're looking good after the move and I saw my alk was quite low so I slowly started increasing my dosages. Things weren't going up, corals looked fine, so I kept going.

Fast forward 2.5 months later and my Ca/Alk are still dog sh-t. Surprisingly, my sand bed isn't a rock.

Magnesium is normal, pH is pretty normal. Very low nutrient tank so I try to dose NO3/PO4.

Recently cleared some precipitate out of my pump but not crazy enough to account for these dosages. I also don't have a clam sucking up a ton of 2-part.

Waiting on an ICP test. Please let me know what you think is going on. I'd love to get to like 420ppm & 8.5 dKH and see some coralline growth.

Took a purposely ugly pic today, just to show the 'natural' state of the tank with uncleaned surfaces. You can tell I have a bit of a nutrient imbalance with dino's on the sand bed. Here is a more flattering tank pic after the tank move (different Pittsburgh apartment).

 

[Tonycass12]

What alk additive are you using. Has it been the same bottle this whole time or different bottles?

 

[Tonycass12]

BTW where are the fish? Lol

 

[Spencer]

What alk additive are you using. Has it been the same bottle this whole time or different bottles?

Details in notes below test results. BRS 2-part. Just last week, I mixed up some more Ca to fill the dosing container. Topped off the alk container.

You can see the two fish (Talbot's and six line) in the dirty tank pic. I added them after the move just to get some more nutrients in the tank.

 

[Randy Holmes-Farley]

How much total two part per day? Or better yet, how much in dKH per day?

 

[Spencer]

How much total two part per day? Or better yet, how much in dKH per day?

So dosages are on that table in my first post. Right now I'm dosing 31.5 mL of Ca and 37.5 mL of Alk daily (between three doses, which are offset by an hour). 69mL of two part daily total.

About 40gal of water volume.

On 8/17-8/19 I did three tests, 24 hours apart. Then a test on 8/21. Alk tested at...

Day 1: 5.4
Day 2: 5.7
Day 3: 5.4
Day 5: 5.8

Does that help?

 

[Spencer]

Also, growth has, if anything, stalled during this effort to increase Ca/Alk.

If growth was accelerating, I would just keep going. But it hasn't been the case. Also, like I said, precipitation is minimal (compared to situations in the past, where my alk/pH has gone extra high).

 

[Tonycass12]

What tests are you using? I'm very curious with whats going on here

 

[Spare time]

Details in notes below test results. BRS 2-part. Just last week, I mixed up some more Ca to fill the dosing container. Topped off the alk container.

You can see the two fish (Talbot's and six line) in the dirty tank pic. I added them after the move just to get some more nutrients in the tank.

sodium bicarb or sodium carbonate?

 

[Spencer]

sodium bicarb or sodium carbonate?

What tests are you using? I'm very curious with whats going on here

Sodium carbonate (BRS Pharma Soda Ash)
Tests are listed in the screenshot of first post.

Red Sea for Ca, Hannah Checker for Alk

 

[Spare time]

Sodium carbonate (BRS Pharma Soda Ash)
Tests are listed in the screenshot of first post.

Red Sea for Ca, Hannah Checker for Alk

Sodium carbonate needs to be dosed very slowly, almost in a drip if possible and into a high flow place. I had an issue a while ago where I kept raising the alk dosage but the alk level never seemed to go up much. I realized I was causing the carbonate to precipitate by adding too much at once

 

[Spencer]

Sodium carbonate needs to be dosed very slowly, almost in a drip if possible and into a high flow place. I had an issue a while ago where I kept raising the alk dosage but the alk level never seemed to go up much. I realized I was causing the carbonate to precipitate by adding too much at once

Yea, so I dose directly at the mouth of where the filter sock goes in the Red Sea sump. (waterfall)

The soda ash 'cloud' dissipates immediately. Highest flow section of my sump. The Ca/Alk doses are offset by an hour.

 

[Randy Holmes-Farley]

So dosages are on that table in my first post. Right now I'm dosing 31.5 mL of Ca and 37.5 mL of Alk daily (between three doses, which are offset by an hour). 69mL of two part daily total.

About 40gal of water volume.

On 8/17-8/19 I did three tests, 24 hours apart. Then a test on 8/21. Alk tested at...

Day 1: 5.4
Day 2: 5.7
Day 3: 5.4
Day 5: 5.8

Does that help?

I guess in my phone the right hand side of the table was cut off because I looked for it before. I do see it now.

You are now adding about 1.1 dKH per day. That’s not very high and unless you see obvious precipitation issues, I’d up the dose.

Even a soft coral tank with coralline algae can use 2 dKH per day.

 

[Spencer]

I guess in my phone the right hand side of the table was cut off because I looked for it before. I do see it now.

You are now adding about 1.1 dKH per day. That’s not very high and unless you see obvious precipitation issues, I’d up the dose.

Even a soft coral tank with coralline algae can use 2 dKH per day.

Hm, okay. It just makes me nervous. I either attribute the issues to my increased dosing (bad test kit, other element out of whack, precipitation) and reduce the dosages...OR I double-down and keep increasing (AKA assume that coral had caught up to the low alk levels).

I just did a 10gal water change and increased my dosages to 51mL Alk (+36%) and 39mL Ca (+24%). The dosing times of the two components are also now offset by 2hrs vs. 1hr.

 

[Spencer]

Update:

Yesterday, I did a 10gal water change where I also added some alk to the clean, new SW. Dumb idea.
_________________________________________________________
As Randy wrote in a 2020 thread...
"The precipitation event caused by the addition of excessive limewater (kalkwasser) causes a big drop in alk that can actually drive the alk much lower than it was before the event.

That is because all of the fresh calcium carbonate surfaces act as seed crystals for more precipitation, potentially dropping the alkalinity to the levels you see."
_________________________________________________________
And that's exactly what happened. The water turned cloudy for ~12 hours and the glass got coated with white precipitate. Looks like a bacterial bloom or weird smudges on the glass, however was obviously precipitate when I went to scrap the glass.

Now my alk just tested at 4.3 (twice).

Basically, after trying to increase my alk slowly with excessive caution for months...I went too aggressive in one hour. Now it's back to slow going. Let's hope the drop wasn't too much for these frags.

 

[Gatorpa]

Why not just mix up some baking soda?
That should get the bump you’re looking for.

 

[Spencer]

Why not just mix up some baking soda?
That should get the bump you’re looking for.

Just because we're talking to two carbonate ions vs. one? Is baking soda less prone to causing precipitation events?

I'll dissolve in DI water but is there any other concern I should be mindful of with bicarbonate, specifically?

Why does BRS (seemingly) prefer carbonate? Thank you in advance.

Note: I don't want to raise my pH, so it looks like I shouldn't bake...

 

[Kellie in CA]

Following.

Struggling to get my alk to at least 7 in my new 40g.

 

[Gatorpa]

Just because we're talking to two carbonate ions vs. one? Is baking soda less prone to causing precipitation events?

I'll dissolve in DI water but is there any other concern I should be mindful of with bicarbonate, specifically?

Why does BRS (seemingly) prefer carbonate? Thank you in advance.

Note: I don't want to raise my pH, so it looks like I shouldn't bake...

If i’m not mistaken that’s why.
There is a thread in reef chemistry where randy breaks it down.
More bang for the buck.

Mix a table spoon in some tank water (say 500ml) slowly so it doesn’t precipitate. you can slowly drip into sump..

 

[Spencer]

If i’m not mistaken that’s why.
There is a thread in reef chemistry where randy breaks it down.
More bang for the buck.

Mix a table spoon in some tank water (say 500ml) slowly so it doesn’t precipitate. you can slowly drip into sump..

Okay, I'm making a small batch of Randy's Alk Recipe #2 (2 cups water, 37g baking soda).

I can understand two ions being twice as effective for raising alk, however I don't see how the risk of precipitation goes down (if you're saying it does).

Maybe it's a matter of bicarbonate not raising pH as significantly as carbonate.