Dosing: Thought I Knew What I Was Doing

[Mikedawg]

I have a RedSea 260 with a significant coral load running for about a year now. I test fairly regularly and noticed my Alk and Ca beginning to drop and so I began adding Kalk through my ATO and switched to RedSea Coral Pro salt about 4 months ago. Couldn’t get my numbers up from around 7 and 390 and so I recently bought a good doser and set it up today. BTW, my corals, especially acros, look pretty good.

Here’s my problem. Last Wed my Alk read 6.0 (Hanna and Salifert), Ca 340 (RedSea) and Mg 1400 (RedSea). Ph was 8.2, nitrate at 2 and phosphate barely detectable. I am trying for Alk of 9, CA of 420 and Mg of 1350 per BRS recommendations. I have not changed water for 16 days and realize that the tank didn’t benefit from the high Alk and Ca in Coral Pro salt. Normally, I do a 15% change weekly.

So, using the BRS calculators and pharma pouch products, I hand dosed sodium bicarbonate (Alk) and calcium carbonate (Ca) for the next three days at specified levels, and got these readings on Sat - Alk 6.3, CA 370 and Mg 1400. I spread out my dosing during this time period in order to avoid raising Alk and Ca by more than 1.4 and 50 ppm each day respectively.

So, I understand that before I begin dosing, I need to get my numbers up to target levels, then calculate coraL uptake values over a couple days to get an estimate of how much to dose to raise Alk and Ca. I cannot understand why my numbers won’t budge and it is hard to imagine that my corals use that much. However, I did test Alk today using Hanna checker for Alk and got a reading of 5.7 which according to this small sample, would mean my uptake is .6 dkh per day.

How can I raise my current levels to target values given this experience? Could it be that I am trying to raise them too fast? I haven’t noticed any signs of precipitation and have been careful to add in chemicals slowly and over two hours time. I use good, current test kits and try to be careful with titration, etc.

Thanks for any and all help; I am about ready to just set my new doser on 50 ml for both Alk and Ca and see what happens!

 

[Randy Holmes-Farley Verified Community Expert]

0.6 dKH alk consumption is on the low side, but there isn't usually much demand at all when the alk drops below 6 dKH.

let's take a step back and see if the kits are giving reasonable results. Try them on some new salt water and see what you get.

I'm suspicious of the calcium reading, unless you are using a low calcium salt mix for water changes.

 

[Mikedawg]

0.6 dKH alk consumption is on the low side, but there isn't usually much demand at all when the alk drops below 6 dKH.

let's take a step back and see if the kits are giving reasonable results. Try them on some new salt water and see what you get.

I'm suspicious of the calcium reading, unless you are using a low calcium salt mix for water changes.

Thank you, good to know my Alk uptake isn't too extreme, and I do want to increase my values of course. I imagine you would have alerted me if you thought I was near "crashing" with the readings I posted.

I will "calibrate" my test kits against freshly mixed Coral Pro salt water and post the results tomorrow after dosing 50 ml of sodium bicarb and calcium carb today which should raise my Alk by .6 dKH. BTW, Coral Pro mixes at 480 ppm according to the label.

 

[Mikedawg]

Randy, looks like you were right. My Red Sea Ca test kit was way off compared to advertised values on Coral Pro salt; in fact the cheap API was more accurate. I'll test more over coming days using other/new test kits to find valid/reliable results.

 

[BlakeP]

Any updates on this? I’m experiencing the same situation.

 

[Mikedawg]

Any updates on this? I’m experiencing the same situation.

I took the plunge and started dosing two days ago what I estimate is 56 gallons with 50 ml sodium bicarbonate for alkalinity and 50 ml of calcium carbonate and my alk just measured 7.8 with a Hanna Checker. I did "spike" alk with 50 ml of Red Sea's Foundation B last night which helped for sure. Still have to test for several more days before I get too excited.....and think I'm on the right track. I'm thinking that I might have been dosing too much previously, although I didn't see signs of precipitation.
What kind of numbers do you have and what are you doing to raise them?

 

[BlakeP]

Well I have a 10 gallon sumped tank with a total water volume of 20 gallons. So much smaller but same issue. I am currently dosing 7ml of soda ash and calcium daily via doser. I can supplement alk with 27ml of sodium bicarbonate and get it to come up to about 7.7 from 7.0. But by the next day it’s back down to 7.0. That’s with the doser running. I have had some precipitation as I’ve tried dosing anywhere from 5ml per day to 14ml. Nothing seems to be working. I’m lost.

 

[Mikedawg]

Understand all too well. Assume you used a dose calculator, valid/reliable test kits, identified uptake, etc. and still can't predict effects of dosing. I'm thinking of starting over once I get new test kits and calibrate them against published values of RS Coral Pro salt. Or maybe, I'll get lucky and what I have been dosing the past two days will eventually produce my target values. "Even a blind pig finds an acorn every now and then" is a notion I subscribe to.
Alk of 7 is low end of good, so you're okay there. Could your uptake be .7? Randy indicated above that .6 certainly isn't unusual. Maybe you should consider increasing dosing amounts and evaluate carefully so you avoid large scale swings.
Good holidays

 

[BlakeP]

I did stop all dosing a week ago and determined that my alk usage was about .7 so I started the doser using that estimate. Alk just won’t move up even with calcium dosed at the same rate. Magnesium is fine as well. I’ve had the dosage anywhere from 5ml to 14ml per day. My only other option would be to decrease the dose to 3ml but that is below what the BRS calculator recommends. ??

 

[BlakeP]

Ok so I stopped all dosing and changed 25% of my water and my alkalinity was 8.6 after my water change. I just checked it 24hrs later and it’s 7.0 Any ideas what’s causing this issue?

 

[BlakeP]

Only other bit of info is when I started the tank 8 months ago I was topping off with Kalk and couldn’t get my alk up so I continued to dose at max Kalk saturation. I eventually had precipitation. I’ve heard that the precipitation residual can act like a magnet and attract newly added alk to predicate out further lowering alk. Any idea if this is correct? If so how can it be corrected?