Need some help with Alk - normal or not?

[mermaid_life]

Hi, I'm a little lost on what to make of my numbers - normal or not? I have a Redsea Reefer 350 that has been up for about 4 years now. It's a mixed reef that's been doing pretty well for the last 2 years.

Parameters:
Mg: ~1400 (trident and Salifert verified)
Ca: ~440 (trident and Salifert verified)
Alk: used to be 8.5, but I've been having trouble getting it above 8 for the last few months or so (trident and Salifert verified)
pH: 8.2 to 8.48 cycle *measured with Apex Probe only

This is my second tank and my experience from my first tank was that San Diego water consistently mixed at low pH (7ish) no matter what salt I used. So, when I started dosing with this tank, I chose to use Seachem Reef Buffer to maintain alk. For a while, the tank nicely peaked at 8.3pH. Then over the last 6 months, pH kept climbing to current day numbers. In my research, I read that pH can affect ALK usage and I'm wondering if that is what is happening here?

My Seachem Buffer is mixed at 33.5g/liter and I have to dose 350mL of that solution per day to push to maintain 7.25dkH (as of today). When it is dosed into my tank, the solution is briefly cloudy but seems to dissipates immediately. I don't see any excess buildup of calcium on pumps or anything... just lots of coralline that I maintain to try to bring down alk usage. There is an hour window between dosing Ca and Alk.

Let me know if there is any other info I can provide. Thank you all in advance for another pair of eyes on this.

 

[mermaid_life]

To help with the math a bit..... Seachem sent me a calculator. ~350mL of the solution equates ~2.5 meq/L daily dosing. I believe this is 7dkH per day.

 

[gbru316]

I'd start by choosing something other than Reef Buffer to maintain your alkalinity. The excess borate may be contributing to your issue.

See this thread:

How to add Seachem Reef buffer?

I need to preface this by saying im still new to reef tanks, only been doing it for about 2 months, and my tank is doing pretty well. I need to bump by alkalinity from 7 to 10 and my pH from 8 to around 8.4. I got some Seachem Reef Buffer and I'm a little confused on how to use it. I need to add...

www.reef2reef.com

Generally, it's better to dose for alkalinity and remove CO2 for pH. Baking soda, or baked baking soda (if you need a larger pH boost) is a far cheaper alternative. Kalkwasser is a good method, too.



Also, this is concerning:

this is my second tank and my experience from my first tank was that San Diego water consistently mixed at low pH (7ish) no matter what salt I used.

Are you using RO/DI?

 

[Screwgunner]

I have a 120 gallon system I use reef builder my tank uses 5 gallons of water per week for top off I am at 2 and 1/4 teaspoons per 5 gallons of make up water. It keeps me at 7.5 alk when everything is good it goes up to 3.5 teaspoons I think it depends on your coral.

 

[mermaid_life]

I'd start by choosing something other than Reef Buffer to maintain your alkalinity. The excess borate may be contributing to your issue.

See this thread:

How to add Seachem Reef buffer?

I need to preface this by saying im still new to reef tanks, only been doing it for about 2 months, and my tank is doing pretty well. I need to bump by alkalinity from 7 to 10 and my pH from 8 to around 8.4. I got some Seachem Reef Buffer and I'm a little confused on how to use it. I need to add...

www.reef2reef.com

Generally, it's better to dose for alkalinity and remove CO2 for pH. Baking soda, or baked baking soda (if you need a larger pH boost) is a far cheaper alternative. Kalkwasser is a good method, too.



Also, this is concerning:

Are you using RO/DI?

Thank you for the thread! I'll read up on it right now.

I am making my own RODI. I think San Diego water is just lower in pH....

 

[mermaid_life]

I have a 120 gallon system I use reef builder my tank uses 5 gallons of water per week for top off I am at 2 and 1/4 teaspoons per 5 gallons of make up water. It keeps me at 7.5 alk when everything is good it goes up to 3.5 teaspoons I think it depends on your coral.

If I'm doing the math correctly, your system is ~2x mine and using the same amount of alkalinity per day.

I'm going to switch to reef builder slowly and see how my pH handles the change.

 

[Screwgunner]

Thank you for the thread! I'll read up on it right now.

I am making my own RODI. I think San Diego water is just lower in pH....

No matter what water you have after it is filtered rodi it should be at 7 neutral.

 

[mermaid_life]

No matter what water you have after it is filtered rodi it should be at 7 neutral.

Oh i didn't know that! Ok. So I really should see how this tank is with pH on it's own without help.

 

[Screwgunner]

Oh i didn't know that! Ok. So I really should see how this tank is with pH on it's own without help.

Tour salt nix sets your ph.

 

[mermaid_life]

Tour salt nix sets your ph.

This I understood. For some reason I just thought that my San Diego water prevented the salt to achieve what the manufacturer claimed. My freshly mixed salt used to be 7.5ish if my memory serves. Red Sea claims that it should mix to 8.2-8.5 range.

 

[Mike1970]

Kalkwasser is your friend

 

[mermaid_life]

Kalkwasser is your friend

Thank you. I should probably see if this buffer is artificially increasing my usage first. Otherwise, I'll probably hit saturation limit pretty quick with kalk if this is truly my tank demand!

 

[Randy Holmes-Farley Verified Community Expert]

A few comments.

0 ppm tds RO/DI water will not read pH correctly, because the ionic strength and buffering is too low for proper pH probe function.

Second, totally pure fresh water will have a pH about 7, but on contact with air, the CO2 enters the water and drops the pH into the 6’s or 5’s.

Finally, totally pure fresh water at pH 7.0 added to seawater at pH 8.1 will actually raise the pH for complicated chemical reasons. Thus, it is never a cause of low tank pH.

 

[gbru316]

If I'm doing the math correctly, your system is ~2x mine and using the same amount of alkalinity per day.

I'm going to switch to reef builder slowly and see how my pH handles the change.

Kalkis going to be your best bet to both raise pH and alk.

and it’s cheaper than reef builder.

why the need to stick with the seachem products?

 

[mermaid_life]

A few comments.

0 ppm tds RO/DI water will not read pH correctly, because the ionic strength and buffering is too low for proper pH probe function.

Second, totally pure fresh water will have a pH about 7, but on contact with air, the CO2 enters the water and drops the pH into the 6’s or 5’s.

Finally, totally pure fresh water at pH 7.0 added to seawater at pH 8.1 will actually raise the pH for complicated chemical reasons. Thus, it is never a cause of low tank pH.

Thank you very much! I just read the thread that gbru316 linked where you mentioned borate alkalinity. It's a bit worrisome since I've been using this buffer for 3 years now.

Do you have any thoughts on the alkalinity usage based on my tank size and load? I will switch to Reef Builder immediately. Anything I should be aware of?

 

[mermaid_life]

Kalkis going to be your best bet to both raise pH and alk.

and it’s cheaper than reef builder.

why the need to stick with the seachem products?

I'm worried that my tank is currently beyond the kalk saturation point so I can't use it anyway. Also, isn't 2 part dosing a lot more controllable? My understanding is that kalk is added in the top-off water which would mean dosing would rely heavily on my tank evap rate. Am i mistaken?

 

[gbru316]

I'm worried that my tank is currently beyond the kalk saturation point so I can't use it anyway. Also, isn't 2 part dosing a lot more controllable? My understanding is that kalk is added in the top-off water which would mean dosing would rely heavily on my tank evap rate. Am i mistaken?

kalk can be dose just like a 2 part. But you don’t need the 2nd part because it’s included.

I’m not entirely sure you know your actual consumption because of the borate. Someone who knows chemistry better than I would have to speak to that. But to me, your tank doesn’t seem excessively stocked with stony coral or coralline.

Its been years since I’ve used kalk but, although it might take a supersaturated slurry, I’d be surprised if you were unable to dose enough. I’ve seen some very heavily stocked SPS tanks running on kalk.

 

[mermaid_life]

I’m not entirely sure you know your actual consumption because of the borate. Someone who knows chemistry better than I would have to speak to that. But to me, your tank doesn’t seem excessively stocked with stony coral or coralline.

Totally agree. That's why I saw it odd that it was consuming so much. I'll switch to builder for now just to see if it changes uptake at all and then depending on results, I'll consider learning something new lol and switching to Kalk.

 

[Randy Holmes-Farley Verified Community Expert]

Totally agree. That's why I saw it odd that it was consuming so much. I'll switch to builder for now just to see if it changes uptake at all and then depending on results, I'll consider learning something new lol and switching to Kalk.

Reef Builder is fine as an alk supplement, but it is not better than ordinary baking soda (baked first, if you also want a pH boost).