Sulphur denitrator usage, ph problem

[billydv]

I have a sulphur denitrator, korallin s series. It's been in use for a while but im fighting a low ph problem. Just checked effluent. Nitrate 0, Nitrite 0, ph 7.8, phosphate 0.15 to 0.20. Flow is dripping almost to point of a slow stream. Effluent is directed to a media reactor filled with aragonite. Tank ph approximately 8.1. Also have a red cyanobacteria issue in main tank. Trying to keep ph up but controller keeps dosing kalwasser to maintain ph. Are sulphur denitrators that much of an issue for ph? How am I dealing with cyano?

 

[Gumbies R Us]

Bumping your post!

 

[jda]

You could post this in the chemistry forum and see if they know. I ran one and it did not move my pH. pH issues are usually from too much co2 in the home that builds up over the summer or winter when people do not air out their homes. However, there are processes in the tank that can lower pH, but also some that raise it. If you have not aired out your home lately, then it will help regardless of what the reactor does.

FWIW - tank pH of 8.1 is nothing to worry about, IMO.

Sulphur reactors do deplete alk, so keep an eye on that.

 

[billydv]

So living room has windows opened, thats not the issue. The effluent is running 7.8. The kalkwasser dosing is maintaining ph of 8.15 with a couple of pumps every few minutes. It's not bad, i just assumed it could have been better. In any event, nitrates and phosphate are practically zero

 

[Randy Holmes-Farley]

Sulfur denitrators will tend to reduce alk and pH. How much of an issue that is depends on how well the tank is aerated and with what sort of CO2 level in that air.

This has more:

Sulfur Denitrators

In these systems, bacteria use elemental sulfur and produce N2 from the sulfur and nitrate according the following equation (or something similar):

2 H2O + 5 S + 6 NO3– → 3 N2 + 5 SO42- + 4 H+

The production of acid (H+) in this reactor can tend to reduce the aquarium alkalinity. It has also been suggested to pass the effluent of such a reactor through a bed of aragonite to use the acid (H+) produced to dissolve the calcium carbonate, and thereby provide calcium and alkalinity to the aquarium. While that is a fine idea, it doesn’t add much calcium and alkalinity to most aquaria.

To estimate the magnitude of the effect, we start with a liberal estimate of how much nitrate might be removed. Say 10 ppm of nitrate per week.

10 ppm nitrate = 0.16 mmole/L of nitrate

Since 4 moles of H+ are produced for every 6 moles of nitrate consumed, this will produce

0.107 mmoles/L of H+ per week

How much calcium this could produce?

Assume that it takes one proton to dissolve one calcium carbonate:

CaCO3 + H+ → Ca2+ + HCO3–

Clearly, this is a substantial overestimate because much of the acid will be used up driving the pH down to the point where CaCO3 can even begin to dissolve. Consequently, we have an upside limit of 0.107 mmoles of Ca2+ per week. Since calcium weighs 40 mg/mmol, that’s 4.3 ppm Ca2+ per week.

For comparison, an aquarist adding 2% of the tank volume in saturated limewater daily is adding on the order of 16 ppm of calcium per day. Consequently, this method may not be especially useful for maintaining calcium. Additionally, the acid produced will have a long term lowering effect on the alkalinity. In fact, it is double dipping on the alkalinity depletion since alkalinity is consumed when the nitrate is produced, and again when

 

[billydv]

Hi Randy,
Thanks for your reply
I believe the tank is super well aerated. Protein skimmer pulls air from outside the house, also that air is pulled through an ozone generator. The is a trickle tower which has a high volume air pump pushing air into the chamber where water trickles down. Even with all that, our living room usually has open windows most of the year.
I do in fact have a reactor which the effluent passes through prior to returning to the sump. Installation of this aragonite filled reactor has helped the situation. Still effluent from aragonite reactor is still 7.8. To combat this constant push downwards from the desired 8.1, I have a self built kalkwasser dosing system. It consists of a 5 gallon reservoir with a small gear motor and a plastic mixing paddle. Water is replenished via a float switch and a soleniid valve connected to RODI water system. A ph controller turns on an industrial type metering pump which pulls the mix and pumps it to the aquarium via 5/16 tubing. It's sent to the tubing just before the filter sock so that the white powder film remains in the filter sock and not all over the sump. Ph electrode is placed just past filter sock so after a pump or two, ph is quickly elevated in sump and shuts off metering pump. This stabilizes throughout the aquarium and about 10 minutes later another pump or two.
The end result is an aquarium with a ph that's always between 8.10 and 8.12. Unfortunately this all seems to be very complicated, it's fine for me but I question the usage of a sulphur denitrator for the average aquarist. Especially when algae scrubbers are now much more advanced, less maintenance nowadays, easier to harvest algae