Need help ! Alk over dosing .

Alan600 · Jan 5, 2015

I was dosing for mg but for some reason I grab alk jug . My tank needs about 40 ml of alk to rise it up 100 ppm . I've read that it's not safe to rise it up more then 100ppm a day . I added about 60 ml of alk be for I realize that it wasn't mg that I was dosing . I did a quick 5 gal wc . I just want to know if my corals would go in to shock for adding to much alk ?

Randy Holmes-Farley · Jan 5, 2015

What is the alkalinity now?

Is it a ULNS SPS system? That's the main type if reef tank where alkalinity changes are a big concern.

A 50% overdose on one day's alkalinity dosing is not usually a concern.

Alan600 · Jan 5, 2015

I'm sorry I meant to say 1 dkh . I tested last night it was at 8.3 dkh and tested this morning . it went from 8.3 to 10 dkh

Alan600 · Jan 5, 2015

My is zoa Dominant . I have about three or four sps .

Randy Holmes-Farley · Jan 5, 2015

I expect that is fine if it is not a ULNS system (ultra low nutrient system).

Alan600 · Jan 5, 2015

Hey randy I got a question . What do you mean by ulns ? Or how do you know you have a unls ?

zemuss · Jan 5, 2015

Are you dosing anything to keep the Nitrates and Phosphates at zero? Or using a ATS to keep them in check?
This is a ULNS.

Alan600 · Jan 5, 2015

Oh okay . No I'm not using anything I just do a 20% wc every two weeks .

Randy Holmes-Farley · Jan 5, 2015

You'll be fine.

UK_Pete · Jan 5, 2015

Randy, I wanted to reduce my alk recently from 9 to 7, as some seem to think this is optimal in ULNS and I want to help some frags survive as much as possible. I used hydrochloric acid, thinking the only result would be negligible sodium chloride increase. Is that right? I have done it over several days btw.

Alan600 · Jan 5, 2015

Oh yeah that's good news . I was freaking out . I also have read you get better growth with alk being around the 7-8 dkh is that true ?

Randy Holmes-Farley · Jan 5, 2015

UK_Pete said:
Randy, I wanted to reduce my alk recently from 9 to 7, as some seem to think this is optimal in ULNS and I want to help some frags survive as much as possible. I used hydrochloric acid, thinking the only result would be negligible sodium chloride increase. Is that right? I have done it over several days btw.

The only other effect is a big but temporary drop in pH. Spreading it out helps deal with that concern.

Randy Holmes-Farley · Jan 5, 2015

Alan600 said:
Oh yeah that's good news . I was freaking out . I also have read you get better growth with alk being around the 7-8 dkh is that true ?

The scientific literature shows some hard corals grow better at higher alkalinity, and I've not seen any data suggesting lower alkalinity is better from that standpoint, so I would not say you get better growth at lower levels. But some corals may have better color, and those in a ULNS environment may have issues with high alkalinity that are not easily understood, but it seems bad for them.

Alan600 · Jan 5, 2015

Oh okay I see , I keep mine in the 9dkh and I seem to get good color in my zoas .

UK_Pete · Jan 5, 2015

Randy thanks, I didn't think to check the pH because I thought the bicarb / carb buffer would prevent significant swings, but I obviously need to read up a bit on that. Did you cover the calculations in any of your past articles?

Randy Holmes-Farley · Jan 5, 2015

It is not trivial to calculate the pH change, but it is quite significant if done all at once. I determined it in one of my articles for a 1.4 dKH drop. I'll look it up later.

Randy Holmes-Farley · Jan 5, 2015

Alan600 said:
Oh okay I see , I keep mine in the 9dkh and I seem to get good color in my zoas .

That sounds good. I think the effect of alk on color is small and mostly an SPS thing.

Alan600 · Jan 5, 2015

It's could just be me . Thanks so much randy for the help .

UK_Pete · Jan 6, 2015

Thanks Randy, I seemed to remember some article where you mentioned HCl but I couldent find it with google because I can't remember the main subject. Would be interesting to see what happens to pH. I've got one addition left today and will check the pH before and after but its always useful to know the theoretical aspect too.

Randy Holmes-Farley · Jan 6, 2015

UK_Pete said:
Thanks Randy, I seemed to remember some article where you mentioned HCl but I couldent find it with google because I can't remember the main subject. Would be interesting to see what happens to pH. I've got one addition left today and will check the pH before and after but its always useful to know the theoretical aspect too.

OK, here's where I tested it:

Chemistry And The Aquarium: The Relationship Between Alkalinity And pH ? Advanced Aquarist | Aquarist Magazine and Blog

In it I tested several additives, including HCl to drop alkalinity by 0.5 meq/L (1.4 dKH). The pH of 35 ppt Instant Ocean dropped from 8.1 to 6.91, then recovered to 7.91 in 24 h of aeration, and 8.15 in 120 h.