calcium reactor effluent readings??

[moneytank]

Are these reading right? I finally got my calcium reactor set up. I made an effluent box to hold my ph probe and for the output of the reactor to drip into. Right now to get everything set up i have the solenoid plugged into a regular plug instead of the ph controller, therefore its always open.
I also turned off the kalk reactor. I let the calcium reactor run like this for three days, which i took these readings on the third day. This is what i came up with.
8 am .......effluent ph 6.70 tank ph was 8.00
(all lights are on by 2pm)
3 pm.......................6.63(lowest it got) tank ph was 8.00
6 pm.......................6.75 tank ph was 8.10
11 pm.....................6.93(highest it got) tank ph was 8.19
2 am.......................6.79 tank ph was 8.11
8 am ......................6.70 tank ph was 8.00

keep in mind, i have never had a calcium reactor so i dont know a thing about them :blink

[matt]

Those readings look really good if you're using ARM or something similar for reactor media. You might also check effuent and tank alkalinity. To measure the effluent alk, just use a salifert kit on the low resolution mode (1 drop of dye, 2ml sample) and double the result. It should be around 25dkh.

[fishypets]

The effluent DKH is more important than the P.H. and should be over 30 DKH IMO.

[moneytank]

ok, a few questions then. Those reading are with the co2 always on. Why do i need my pinpoint ph controller then? or can i just use a ph monitor. Prob going to answer my own question here, but...the .2 swing in ph is that ok, or is that why i hook my kalk reactor up to the monitor so it can keep everything more stable(smaller ph swing) . If so, what do i set the high and low for on the controller, assuming i leave the ph probe in my effluent container ?
oh and yes it is using ARM media.
thanks for all the help also................

checking alk now

[matt]

I would not use the ph probe to control your effuent ph, but maybe as a safety feature in case your effluent ph gets too low. If (and that's kind of a big if) you have a reliable way of controlling the CO2 and effluent flow, you should have a very stable effluent ph. Shutting the CO2 flow on and off sometimes makes it more difficult to keep a steady reactor ph, and sometimes the flow varies when it comes back on. You could set it really low, like 6.4 or something.

Effluent dkh is usually very high when the media is pretty new, but will eventually drop to between 20-30 dkh after the initial surface of the media has dissolved. I think this is probably due to the way alk test kits work; they will get skewed if there is any dissolved or particulate aragonite in the sample. What your actual dkh is with regards to ph and effluent flow is dependent on your reactor size, efficiency of circulation, and the ph. ARM seems to have a "sweet spot" around 6.65-6.7.

[discuspro]

So, how do you find the "sweet spot" of any calcium reactor media?

[matt]

What I did with ARM was just continue to adjust the effluent ph, and measure effluent dkh at each ph. Going higher than 6.7 caused the dkh to really drop, and getting much lower than 6.6 didn't raise it that much. I'm sure you could do the same with any media. This was on one of the reactors I built; at the time I was building reactors and trying to get a really efficient design. By efficient I mean high effluent dkh at a given ph. What I found out was that circulation in the reactor is very important, that's why I ended up using Pan world pumps for them with bottom-up flow, and most important, the size of the reactor really matters. More reactor media and a higher reactor water volume means more contact time for the media in the acidic chamber, and better dissolution of the media.

I'm not trying to sound like a know-it-all with reactors; I built several pretty successful ones and was really into the design for a while. If I had a bigger tank I'd be using one again. IMO the biggest issue with calcium reactors for long term use is getting clean media. At low ph, toxic metals are much more soluble in water, and consequently any impurities in the media tend to get passed on to the tank. With KW, impurities in the powder and water tend to get precipitated out in the high ph.

If I were running a calcium reactor again, I'd take a good look at this new Schuran (sp?) media which is unfortunately very expensive but is supposedly very high purity.

[discuspro]

Do you happen to know where I would find that "Schuran (sp?) media"?

[matt]

Premium aquatics carries it, although it's currently out of stock.