When to test parameters after dosing?

duncangweller · Sep 29, 2015

Hi all,

I'm trying to dial in my dosing on my 93 gallon cube tank and in having some troubles.

I'm trying to keep my levels at:

Alk - 2.95meq/8.2dkh
Calc - 420
Mag - 1350

I don't have a problem with mag as that's a once a month kind of dose for me. However alk and cal I feel I am forever chasing.

My alk and cal are dosed automatically with brs dosers. Alk in the morning with a dose every two hours from 02:00 until 10:00. Calc begins at 12:00 and doses every two hours until 20:00.

I typically test my Reef at 11:00 using Hanna Checker and red sea kits.

However, I often find my alk a little high and my calc low, which I assume is because the calc portion hasn't been dosed yet for the day.

My question is, how do I test/ when do I test in order to get an accurate representation of my Reef params?

Is my method of dosing causing me problems or is that on point?

I feel like I've been trying to set these dosers for over a year now and its getting a little frustrating.

Thanks for your help,

Dunc

JimWelsh · Sep 29, 2015

I guess it depends on your demand and how much you are dosing. The higher your demand, the greater the likelihood that it is causing you testing problems.

I have my dosing of both parts evenly distributed throughout the day, with Alk and Ca staggered, so they aren't being dosed at the same time.

GainesvilleReef · Sep 29, 2015

I agree with Jim. I used to dose two part a little of each alternating back and forth throughout the day. I check my Alk once a week and maybe twice if something is changing. Very small salinity swings can affect your results by several ppm. Look for trends and not actual values.

Randy Holmes-Farley · Sep 29, 2015

Can you clarify what you mean by alk a little high and calcium a little low? By how much?

duncangweller · Sep 29, 2015

Alk was at 9dkh and calc was at 345ppm

Randy Holmes-Farley · Sep 29, 2015

If you are suggesting that the calcium dropped from 420 ppm to 345 ppm in one day, that was definitely testing error.
You would also need to use up 10.5 dKH of alkalinity for that to happen, and it is unlikely you dosed enough for it to jump back to 420 ppm.

duncangweller · Sep 29, 2015

Oh no, I didn't mean that. I'm trying to get my levels to what I mentioned in the first post.

However, I'm not sure if by testing when I am that I am getting an accurate measure of my calc as by that time of day my calcium hasn't even been dosed.

Would it be better to stagger my alk/calc dose to say dose alk, wait a couple of hours and then dose alk and repeat throughout the day?

I'm almost certain that I'm over thinking this, I just can't get my head around dosing. In particular, when and how.

Randy Holmes-Farley · Sep 29, 2015

How much of what are you dosing each day?

Calcium isn't going to change much during a single day, and not much before vs after dosing. It just doesn't change very fast.

In terms of time of day, it doesn't really matter when you measure. Combining what you dose with the value before or after dosing will give you the other value, or you can measure them both at least once.

duncangweller · Sep 29, 2015

Ok. I see. At the moment I am dosing 71.5ml of each chemical into my 93 gallon. I have 4 med/large colonies and around 10 frags plus a number of zoas and a large hammer coral.

I'll use your corrections article to get my levels where wanted (8.2dkh & 420ppm calc) by dosing just the calcium portion of my 2 part.

Randy Holmes-Farley · Sep 29, 2015

duncangweller said:
Ok. I see. At the moment I am dosing 71.5ml of each chemical into my 93 gallon. I have 4 med/large colonies and around 10 frags plus a number of zoas and a large hammer coral.

I'll use your corrections article to get my levels where wanted (8.2dkh & 420ppm calc) by dosing just the calcium portion of my 2 part.

That sounds like a good plan.

Assumign this material is like my DIY (as from BRS), then 71.5 mL willb e boosting the calcium by about 8 ppm and alk by about 1.1 dKH.

That calcium change is likely within the uncertainty of your test kit, so it won't matter much when you test it. If you see a day to day difference of 20+ ppm calcium, that is likely testing error.