Alkalinity Drops Considerably

[StevenS01]

For some reason I have a hard time maintaining alkalinity above 8.0. At first I started using BRS additives to raise my alk/cal/mag. For some reason I could never get my alk above 7, and after trial and error I came to the conclusion that the soda ash I was mixing was bad. So I switched to Red Sea and I was very happy with the results, for a while.

When I first started using Red Sea, I was about to keep an all of around 8.5-9, but now I am again experiencing drops in alk, and dose about 150mL a day in my Red Sea reefer 170 to maintain an alkalinity near/barely above 8.0. Part of this I was convinced was my dosing method.

At first I dozed into the powerhead, this was with the BRS additives. When I switched to Red Sea, I dosed the same way, through the powerhead. The reefing community recommended I dose in the return of my sump. Not wanting to buy more tubing for my dosers, I cut out a piece of the overflow top and moved my dosing bracket above my overflow. I don’t feel like this was a good method, because it lead down to the compartment where my Skimmer was and I was struggling to maintain 8.0.

Now the bracket is back above the powerhead, and my numbers are coming up but I’m still using a LOT of solution (150 mL). Keep in mind this is Red Sea Foundation. When I mention that I have a problem keeping alkalinity stable, it is JUST alkalinity. Calcium and magnesium stay constant, Cal read on the high end tonight around 512, Mag is about 1300. It is not out of the ordinary for my alkalinity to drop from 8 to 7.5 throughout the day, it’s almost like I just can’t dump enough in there to keep it up.

I am doing a 10% water change, about 5 gallons a week, with Red Sea coral pro salt. My tank consists of LPS and softies, and most recently I added a few SPS frags. I made a DIY kalk dripper, however I didn’t want to use kalk since my calcium is consistent and stable. I read in some other threads that Red Sea is not a two part and therefore it can be adding in non equal parts, but I feel like I’m doing something wrong. Or are my LPS/SPS really just sucking that much out of the water? Hope to get some help. Thanks all.

 

[Randy Holmes-Farley]

What size tank are we talking about and what is in it? Coralline? It is impossible to judge what a mL dose means without that sort of information.

It is not uncommon to have substantial precipitation of calcium carbonate, especially in newer tanks with lots of raw calcium carbonate surfaces to nucleate more precipitation.

You definitely are consuming calcium along with the alkalinity, but the amount involved (about 18-20 ppm calcium for each 1 meq/L (2.8 dKH) of alkalinity) is too small to readily detect. Red Sea coral pro is also very high in calcium so using it for water changes keeps boosting calcium.

There are a lot of things that can be done to reduce precipitation, but the easiest is to lower the pH (use baking soda or a two part based on baking soda for alk, not a higher pH system based on carbonate) and to lower your alk goal for a while to let the precipitation surface "cool off" and get coated with the stuff that normally reduces precipitation (phosphate, organics, magnesium, etc.).

I'd target just 7.0 dKH for a while. Everything is fine at that alk, and consumption will be lower. When you do additions, add to a very high flow area (not into a powerhead, but maybe just after it). Don't dose next to a heater, since calcium carbonate will precipitate onto it.

FWIW, I'm sure the sodium carbonate from BRS wasn't "bad".

 

[StevenS01]

What size tank are we talking about and what is in it? Coralline? It is impossible to judge what a mL dose means without that sort of information.

It is not uncommon to have substantial precipitation of calcium carbonate, especially in newer tanks with lots of raw calcium carbonate surfaces to nucleate more precipitation.

You definitely are consuming calcium along with the alkalinity, but the amount involved (about 18-20 ppm calcium for each 1 meq/L (2.8 dKH) of alkalinity) is too small to readily detect. Red Sea coral pro is also very high in calcium so using it for water changes keeps boosting calcium.

There are a lot of things that can be done to reduce precipitation, but the easiest is to lower the pH (use baking soda or a two part based on baking soda for alk, not a higher pH system based on carbonate) and to lower your alk goal for a while to let the precipitation surface "cool off" and get coated with the stuff that normally reduces precipitation (phosphate, organics, magnesium, etc.).

I'd target just 7.0 dKH for a while. Everything is fine at that alk, and consumption will be lower. When you do additions, add to a very high flow area (not into a powerhead, but maybe just after it). Don't dose next to a heater, since calcium carbonate will precipitate onto it.

FWIW, I'm sure the sodium carbonate from BRS wasn't "bad".

Hey Randy thanks for the response. The size of the tank is 34 gallons, on top of an 11 gallon sump. I don’t really have any coralline yet, although I might have some forming as I’m starting to get specs on my glass that are to small to identify. Do you think I should just bite the bullet, buy some extra dosing tubes and reroute my dosing tubes into the return?

How do you suggest i approach the situation if I decide to use baking soda to lower the pH in my system?

 

[StevenS01]

What size tank are we talking about and what is in it? Coralline? It is impossible to judge what a mL dose means without that sort of information.

It is not uncommon to have substantial precipitation of calcium carbonate, especially in newer tanks with lots of raw calcium carbonate surfaces to nucleate more precipitation.

You definitely are consuming calcium along with the alkalinity, but the amount involved (about 18-20 ppm calcium for each 1 meq/L (2.8 dKH) of alkalinity) is too small to readily detect. Red Sea coral pro is also very high in calcium so using it for water changes keeps boosting calcium.

There are a lot of things that can be done to reduce precipitation, but the easiest is to lower the pH (use baking soda or a two part based on baking soda for alk, not a higher pH system based on carbonate) and to lower your alk goal for a while to let the precipitation surface "cool off" and get coated with the stuff that normally reduces precipitation (phosphate, organics, magnesium, etc.).

I'd target just 7.0 dKH for a while. Everything is fine at that alk, and consumption will be lower. When you do additions, add to a very high flow area (not into a powerhead, but maybe just after it). Don't dose next to a heater, since calcium carbonate will precipitate onto it.

FWIW, I'm sure the sodium carbonate from BRS wasn't "bad".

I don’t know if this plays any role or not, but I have two 8x8x4 blocks of Marinepure in my sump for extra surface area. I was reading that the nitrogen cycle also uses alkalinity to produce nitrogen. Am I slowing down the consumption of alkalinity by removing one of these blocks? I have an ATS up and running as well. Just an idea I’ve been curious about.

 

[Randy Holmes-Farley]

I don’t know if this plays any role or not, but I have two 8x8x4 blocks of Marinepure in my sump for extra surface area. I was reading that the nitrogen cycle also uses alkalinity to produce nitrogen. Am I slowing down the consumption of alkalinity by removing one of these blocks? I have an ATS up and running as well. Just an idea I’ve been curious about.

Have you been monitoring nitrate?

If nitrate is actually rising, that can deplete alkalinity. A 50 ppm rise in nitrate depletes 4.5 dKH of alkalinity if it came from ammonia.

Steady nitrate between water changes (regardless of the value) means this is not depleting alkalinity because consumption of nitrate returns the exact same amount of alkalinity as was consumed when making it.

My suggestion is to let the alk drop to 7 dKH for a while and maintain it there with baking soda dissolved in fresh water.

 

[Randy Holmes-Farley]

I don’t know if this plays any role or not, but I have two 8x8x4 blocks of Marinepure in my sump for extra surface area. I was reading that the nitrogen cycle also uses alkalinity to produce nitrogen. Am I slowing down the consumption of alkalinity by removing one of these blocks? I have an ATS up and running as well. Just an idea I’ve been curious about.

I doubt this is causing the alk depletion, and if it is, then you do not want to stop it because the conversion of ammonia to nitrate needs to happen somewhere and will have the same effect on alk (per unit of nitrate produced) wherever it happens.

 

[StevenS01]

Have you been monitoring nitrate?

If nitrate is actually rising, that can deplete alkalinity. A 50 ppm rise in nitrate depletes 4.5 dKH of alkalinity if it came from ammonia.

Steady nitrate between water changes (regardless of the value) means this is not depleting alkalinity because consumption of nitrate returns the exact same amount of alkalinity as was consumed when making it.

My suggestion is to let the alk drop to 7 dKH for a while and maintain it there with baking soda dissolved in fresh water.

Thanks Randy. Is there a specific time you recommend maintaining the alkalinity with baking soda?

 

[Octane13]

I have a similar problem with my ALK but I'm not dosing anything. My nitrates hover somewhere in the 10-15 range no matter what I do (newer tank?). Thought my redsea pro test was bad but Im getting 11-12 with newly mixed salt (RC). After a few days it drops to 7, has happend a few weeks in a row and stays there until I do a water change. and my Mag used to swing 200-400 before I started shaking the bag before mixing. Thought that was my original problem with precip. I only have 3 smaller LPS which all seem extremely happy and no real visible coralline growth. Calcium has never dipped below 500 (max titration every time) thoughts?

 

[Randy Holmes-Farley]

Thanks Randy. Is there a specific time you recommend maintaining the alkalinity with baking soda?

Any time is fine.

 

[Randy Holmes-Farley]

I have a similar problem with my ALK but I'm not dosing anything. My nitrates hover somewhere in the 10-15 range no matter what I do (newer tank?). Thought my redsea pro test was bad but Im getting 11-12 with newly mixed salt (RC). After a few days it drops to 7, has happend a few weeks in a row and stays there until I do a water change. and my Mag used to swing 200-400 before I started shaking the bag before mixing. Thought that was my original problem with precip. I only have 3 smaller LPS which all seem extremely happy and no real visible coralline growth. Calcium has never dipped below 500 (max titration every time) thoughts?

Sounds mostly normal to me.

Alk dropping a few dKH in a few days is expected.

What salinity are you using?

 

[Octane13]

Salinity is 1.025 I mix to 1.026 but I have been skimming heavy and the ATO makes up the difference unfortunately

 

[Randy Holmes-Farley]

OK, I'd just keep supplementing alkalinity as needed.