CHANGING SALT TO HAVE LOWER ALK.

mckinleyw · Nov 13, 2017

I do water changes about every other week on my 50 display with 70-80 gal total system. I am currently using reef crystals and my alk. is testing at a constant 13 dkh. I would like to bring this down to around 8 or 9. what is the best way to switch salt mixes? I am thinking about redsea blue bucket.

Should I only change a certain percentage over time? What are your suggestions? I am looking at going to the triton no wc method. My refugium is about 20 gal. well over the 10 percent needed.
I have red macro algae and cheato in there with a kessil H380 lighting it. And I have a large skimmer.
Any other questions/concerns I should be taking into consideration?

The reason I am looking at switching is because im not happy with my coral activity. I have issues with quite a few lps and sps. and very slow growth.

Randy Holmes-Farley · Nov 13, 2017

Just begin using the new salt mix for your regular water changes and it will come down slowly. If you do none, I'd do 10% weekly unless you want this process to speed up.

Or you can add an acid (such as muriatic acid) to your Reef Crystals to lower the alkalinity in it.

That all said, growth will not typically speed up by lowering alkalinity. If anything, higher alk usually leads to faster hard coral growth, as long as there are adequate nutrients (nitrate and phosphate) present.

Have you measured nitrate or phosphate?

mckinleyw · Nov 13, 2017

Randy Holmes-Farley said:
Just begin using the new salt mix for your regular water changes and it will come down slowly.

Or you can add an acid (such as muriatic acid) to your Reef Crystals to lower the alkalinity in it.

That all said, growth will not typically speed up by lowering alkalinity. If anything, higher alk usually leads to faster hard coral growth, as long as there are adequate nutrients (nitrate and phosphate) present.

Have you measured nitrate or phosphate?

I haven't in a while. Ill try to test those this evening. I expect them to be high. ive always had a high nutrient system. This could have changed I guess. I do understand that higher nutrients can reduce grow rates.

Thank you very much for the fast response @Randy Holmes-Farley.

Randy Holmes-Farley · Nov 13, 2017

FWIW, here's an alkalinity lowering recipe copied from an old thread of mine:

Be very careful with straight muriatic acid. It can easily burn you, especially your eyes.

The "acidity" (that being essentially negative alkalinity) of muriatic acid straight from the bottle is about 11,000 meq/L.

So adding 1/11,000 of the water volume as this acid will drop alkalinity by 1 meq/l (2.8 dKH).

If you want a drop of 6 dKH, or 2.1 times that amount, so you'd add 1/5,100th of the water volume.

For example, if you make up 13 gallons ~ 49 L of salt water at a time

1/5100 of 49 L = 9.6 mL

So I'd add 5 ml and stir well for a few minutes and see what alkalinity you get. Then dose again assuming it seems on the right track.

You'll need to aerate well after adding the acid to blow off the excess CO2 and bring up the pH

mckinleyw · Nov 13, 2017

Randy Holmes-Farley said:
FWIW, here's an alkalinity lowering recipe copied from an old thread of mine:

Be very careful with straight muriatic acid. It can easily burn you, especially your eyes.

The "acidity" (that being essentially negative alkalinity) of muriatic acid straight from the bottle is about 11,000 meq/L.

So adding 1/11,000 of the water volume as this acid will drop alkalinity by 1 meq/l (2.8 dKH).

If you want a drop of 6 dKH, or 2.1 times that amount, so you'd add 1/5,100th of the water volume.

For example, if you make up 13 gallons ~ 49 L of salt water at a time

1/5100 of 49 L = 9.6 mL

So I'd add 5 ml and stir well for a few minutes and see what alkalinity you get. Then dose again assuming it seems on the right track.

You'll need to aerate well after adding the acid to blow off the excess CO2 and bring up the pH

Thanx. Didnt get to testing nutreints tonight. Will see about when i get home tommorow.

madweazl · Nov 13, 2017

I'm working out of town and don't have access to my notes but I'm pretty sure I was using 2.3ml muriatic acid to drop 5 gallons of mixed Reef Crystals to 8.0 (close to what Randy demonstrated above which I'm sure is correct). I leave powerheads in the buckets with a hose connected to the venturi and haven't had any issues. I do get nervous handling the muriatic acid and really should invest in some proper protective gear.

I thought @Randy Holmes-Farley had mentioned a safer means of lowering the alkalinity a while back but I cant recall what it was off the top of my head.

Randy Holmes-Farley · Nov 14, 2017

madweazl said:
I thought @Randy Holmes-Farley had mentioned a safer means of lowering the alkalinity a while back but I cant recall what it was off the top of my head.

Sodium bisulfate, which I think is the ingredient in Seachem acid buffer.