alkalinity

[JimmyBeam]

Our Ph is between 8.2 during the day and drops to 7.9 when the lights go out. Our Alkalinity is 11 dkh. Can the alkalinity go higher, should our Ph be higher? How high is too high for the Alkalinity. We have a saltwater reef aquarium with fish and invertebrates. Any help would be appreciated.

[Halelorf]

If you have a sump run the lights on a reverse cycle from the main tank lighting. That should keep your ph from swinging around like that.

[cocoa_pleco]

yep, halelorf hit it

[zackish]

If you have a sump run the lights on a reverse cycle from the main tank lighting. That should keep your ph from swinging around like that.

Expand on that please. What do you mean by reverse cycle?

[cocoa_pleco]

at night, run your sump light while your tank lights are off, and so on as reversed.

[unleashed]

that only works if there is algae in the sump.

[ILuvMyGoldBarb]

True. It requires that you are running somewhat of a refugium in order to reverse that pH swing.

[JimmyBeam]

What type of light should be used on the sump? Flourescents, halides, or actinic? We do have a small refugium that hangs on the tank and we leave that light on at night and it is out during the day, but our PH is still swinging. Should the alkalinity be higher? How high is to high?

[cocoa_pleco]

usually i see power compact lights sideways on sumps, not 100% sure because ive never had a sump

[JimmyBeam]

Thanks for your help, it is greatly appreciated

[ILuvMyGoldBarb]

Your alk is just fine, it actually higher than mine. How big is the tank and how big is the refugium and what exactly do you have in the refugium?

[JimmyBeam]

Tank is 75 gallons, refugium is about 3 to 4 gallons with figi mud and some micro algae

[ILuvMyGoldBarb]

That explains the swings. A 3-4 gallon refugium on a 75 gal tank is going to have almost not effect at all. I've read a number of expert reviews on the figi mud and the opinion of the experts is that is nothing more then a snake oil scheme, it doesn't really do anything. As for the algae, you need a Macro Algae like Calurpa or Chaeto in there. However, even at that size it's not really going to do much. Do you have sand of any kind in the bottom of it? The reality is, for a tank with a volume of 75 gal you really need a refugium with a 10-20gal capacity for it to really have much of an effect, and even at that the best thing it is going to do is produce Pods but it's not a terribly effective Nitrate reducing mechanism.

Are you running a calcium reactor?

[JimmyBeam]

No, but we do have a kalk reactor

[ILuvMyGoldBarb]

What are the details for your setup? I'm kind of working blind here. LOL Give lighting (amount and type), coral types, sump volume, anything and everything will help. Are you using a deep sandbed, how much live rock and how old is the tank? Those will all be important as well.

[JimmyBeam]

Lighting is metal halides not sure of watts, 54 watt t5ho actinic lighting, moon lights, hard corals, softs corals, many variations, 25-30 gallon sump, we have a deep sand bed around 5 -6 inches, 100lbs of live rock, it has been set up about 2 years, stocked for about 1 1/2 years. We also have a clown fish, a foxface fish, a velvet wrasse, a yellow tang and a couple of other fish that I am not sure of the names, we also have snails, shrimp, hermit crabs, and an urchin.

[ILuvMyGoldBarb]

Have you experienced any troubles resulting from the pH swings? If not, then I wouldn't really worry about them too much. You pH is not dipping to dangerous levels. If it was then I'd worry but It's not really that bad. I know people who are extremely successful reef keepers who have a 180gal reef that stays at about 7.96 all the time.

[JimmyBeam]

Haven't really had any problems. Most stuff we read says Ph should stay between 8.0 and 8.4 and a shift of more than .2 is not good. Just trying to stay on top of these things since we are new to keeping the aquarium. Lots invested, don't want things to crash

[ILuvMyGoldBarb]

How long have you been having these shifts?

[JimmyBeam]

Not really sure, used to test daily with the test kit and it tested fine. About two weeks ago, we got a Ph monitor that shows constant Ph readings and we noticed the change between day and night. Could have been going on all along, not really sure. That is why we are questioning whether this is okay or not

[spudbuds]

It likely has been occuring the entire time. Likely not a problem, but it doesn't hurt to smooth out the swing a bit. Add the macro algae to the fuge and increase the fuge size if you can. It may help a bit, but you're still going to get a small swing.

- Bill

[ILuvMyGoldBarb]

I decided to do a little research as to the cause of pH drops during the night in reef tanks and I came up with some rather interesting info. Corals and Macro Algae are both photosynthetic organisms and as such they respire during dark periods. When the organisms respire they release CO2. The release of the CO2 when they respire is what causes the pH drops in reef tanks. In order to prevent a pH swing, you need to ensure that the amount of CO2 being respired during the night equals that being respired during the day. The only way to prevent this 100% is to have the biomass of photosynthetic organisms in the refugium equal that in the main system. Since this is generally not possible there will be somewhat of a pH swing.

As a result of this explanation, the previous recommendation of increasing the size of the refugium will have a double effect. First it will increase nitrate reduction and second it will increase CO2 production during the day this leveling out the pH and decreasing the amoung of the swing.

As a result of all this, the swing probably hasn't been occuring the entire time the tank has been setup, as the biomass of photosynthetic organisms increases, so does the amount of CO2 being released.

[spudbuds]

Yep, I knew that, but it's nice to get the confirmation. I guess I should have elaborated. I could have saved you some research time. The reason I said the swing has likely been happening the entire time is he most likely has always had far more photosynthetic organisms in his display then his fuge (algae in the beginning, corals and algae now). There's no telling how big the swings have been, but they've surely been there.

- Bill