2-part dosage inconsistancy questions...

[20 20]

Vague thread subject, eh? :p

I'm about 5 months into setting up a 125 gallon reef, and decided to use the famous "Randy's 2-part" solutions. (Do ya think I get points for calling it 'famous'?:p ) At first I was dosing it daily, and it would take about 400 ml of both solutions to keep the alk at bout 10 dKH and the calcium at about 430. Keep in mind, the tank is VERY lightly stocked, about 4 small sps, a small blasto, a candy cane coral, and that's about it. Here's the inconsistancy that puzzles me. I've begun using an Aquamedic Reefdoser to dose the solution, a small amount once an hour. At first I set it to total about 400 ml a day, but the alk rose dramatically, up to over 12 dKH in two days. After a couple of weeks adjusting the dosage, I now have the Reefdoser adding about 150 ML a day. The alk is fairly stable, but still rises very slowly.

So, any explaination (other than I'm screwing up my measurements) for needing to dose 400 ML a day when it was added once a day, to needing to dose 150 ML (or less) a day when that is split into once-an-hour dosages?

[BigJPDC]

I was just going to post almost the same thing in a new thread.

I was dosing 10-15mls of dkh buffer a day, to keep me at 9-9.5 dkh, and I was tracking 1 gallon of evap a day as well. I then drained my top off reservoir and filled it with exactly 6 gallons of water and 48mls of buffer - for 8ml\day. Well . . four days later I am now at 11dkh! The highest it's ever been.

Of course the corals and fish look as good as ever, but I thought the idea was to limit the daily interaction.

tagging along, I have a feeling I did some math wrong somewhere.

jp

[Randy Holmes-Farley]

At first I set it to total about 400 ml a day, but the alk rose dramatically, up to over 12 dKH in two days. After a couple of weeks adjusting the dosage, I now have the Reefdoser adding about 150 ML a day. The alk is fairly stable, but still rises very slowly.


Which recipe?

Adding too much of Recipe #1 too fast can cause elevated pH and local precipitation of calcium carbonate, increasing apparent demand.

Ever monitor the pH when adding it?

[20 20]

I've checked my math, rechecked my math, tested the flow rates of the pumps on the Reefdoser, retested those rates, and then re-retested them. I have a BA in Mathamatics, so I can usually add and subtract.

It's the multiplication and the division that gives me trouble... :D

Actually, I received that degree about 27-ish years ago, and don't remember a dang thing. I was trying to help my 16 year old last night with his Algebra-2 homework, and could figure out the first problem, but the 2nd and 3rd? Go get some tutoring, kid!:p

[BigJPDC]

afternoon pH has actually dropped in my case, from 8.45 to 8.35.

[20 20]

I'm using recipe 2, the 'unbaked' baking soda recipe. I never checked 'before and after' PH levels when doing the once a day dosing, but the PH stayed between 8.0 (morning) and 8.2 (evening) when dosing once a day, and has stayed at those levels with the hourly dosing.

[BigJPDC]

Will buffer settle to the bottom of the container, meaning that the pump is sending more concentrated solution to the tank?

[20 20]

Doesn't seem to in my containers.

[Randy Holmes-Farley]

Undissolved buffers would complicate dosage comparisons.

The other issue is that the demand in a reef tank for calcium and alkalinity rises as the alkalinity rises, and falls as it falls. it essentially stops when the alkalinity hits 6 dKH or so. It could be that the demand is simply higher when there is a period when the alkalinity is a lot higher, and when you dose continually, you do not have that elevated period.

[20 20]

Didn't think there'd be a cut-n-dry answer to this one, I was just curious. Seems to be working fine with the hourly dosing, I'll keep that up, and see what happens. Thanks for the answers, Randy.

[Randy Holmes-Farley]

You're welcome.

Good luck. :)