bosmahe1

Very nice! It has me thinking about collecting small stones for the foreground in my tank. It looks like a stream bank with stones in the foreground and plants behind. Curious as to why you crank up the KH so high. Since you are using RO, I would have thought you would shoot for a KH of 4 or less. You might consider getting some more filtration for this tank . I really like this tank. Nature aquariums and dutch aquariums are just not very natural looking to me. This just looks more like something I would expect to see underwater.

AWMBonke

That's about the most high tech tank I've ever seen o.o Very impressive. How did you combine everything so you can regulate it on a computer? Did you find some software somewhere or did you write some custom stuff yourself?

PAUL GRAHAM

Thanks!

The streambank look is what I wanted to get. It needs to have a wild-natural appearance, rather than the highly manicured, or formal, type presentation. The pebbles do impart a wild aspect.

The KH is where it needs to be so I can hold the pH at a reasonable value (6. and get at least 30 ppm CO2. This is a high light system and I inject CO2 for robust growth. There is no need to hold down the KH for any particular reason, as the fish are fine with it. Just now the GH is a little higher than normal, as I try to keep it around 110 ppm (6 degrees) also, but there is no harm in the higher value.

I know this looks like a lot of filters, but for a tank this size, the turnover rate is about right. I don't do much by halves!

PAUL GRAHAM

The system is run by a Neptune Systems Apex Aquacontroller. It monitors Conductivity, Redox Potential (ORP), Temperature, pH, and Dissolved Oxygen (DO). It controls pH by switching the CO2 solenoid and limits DO depletion by switching aeration (air-pump). It also does the auto top-off by switching the fill pump from the RO reservoir. It also times the dosers, the sterilizers, cooling fans, and the lights. It has gobs of timer and switching capacity, limited pretty much by how many Energy Bars you have. It interfaces with the computer via ethernet and is entirely firmware driven. I really like it.

Reefers use these systems mostly, but they are perfectly okay for FW systems too. I have all this reliable automation plus manual over-rides and easily changeable programming with a small PC and a mouse. Did I say I really like it?

PAUL GRAHAM

I don't get what's with the smiley face. I typed (6..

Did it again!

PAUL GRAHAM

Hey I looked at those KH and GH numbers again. I have something backwards here don't I? I will do new tests right away and set the record straight.

bosmahe1

I have a KH of 5 and GH of 7 on average coming out of the tap and the PH is about 6.2 when my drop checker is yellow. So at least 30 PPM CO2. If I were using RO, I would probably shoot for a KH of 4 and GH of 5. I wouldn't mind the PH hitting 5. But on the other hand, my plants probably don't need water that soft anyway.

PAUL GRAHAM

Okay... I needed to do some chemistry adjustments. Some water changes and buffer additions reset the water column. The KH has been creeping upwards for reasons uncertain.

My target KH is 6 - 8 degrees because I want to keep the CO2 at around 30 ppm without the pH going too low. I like to keep it at around 6.8 because that is inside the optimum growth curve for aerobic bacteria.

bosmahe1

Hmmm, interesting. Do you have more info on that? I have heard that acidic water isn't ideal for bacteria but don't know the ideal PH ranges. My tap usually has a PH of 7.2 and my tank is usually at 6.2 to 6.4. My KH varies from 5 to 6 I think.

PAUL GRAHAM

Grady, et al: Biological Wastewater Treatment; CRC, 1999

Chapter 3 - Stoichiometry and Kinetics

"Although all bacteria grow poorly outside of the normal physiological pH range of 6.0 to 8.0, nitrifying bacteria are particularly sensitive to pH, especially Nitrosomonas...[reference here made to a bell-shaped curve]... It can be seen that the [growth/activity] rate reaches a maximum at a pH of about 8, and declines sharply for lower pH values. A wide range of pH optima has been reported, but most workers agree that as the pH becomes more acid the rate of ammonia oxidation declines."

Chapter 11 - Biological Nutrient Removal

"Available data indicate that the activity of nitrifying bacteria is significantly reduced as the pH drops below 7.0... Much of those data were collected in batch reactors using unacclimated cultures, but laboratory studies using acclimated cultures suggest that nitrifiers can acclimate to lower pHs, in the 6.5 to 7.0 range, with little decrease in activity. Many nitrifying [treatment processes] operate quite successfully at pH values in this range, with efficiency dropping off only as the pH drops below 6.5. This potential should be considered in the design and operation of biological nutrient removal systems."