Cyano and a denitrifier or?

[aaparkr]

Ask me anything. I've got a weekly log dating back to may 26 of 2003 when I started this hobby in a 55 gallon.

Where I am today is a 75 gallon with T5 lights that hasn't changed significantly in years, but has been changing a little bit every few weeks ever since I got started.

I've had a problem with nitrates because of the 1 fish I got when I got the tank in 2003. Who knew a little clown would turn into the devil fish that dominated the tank. After starving a yellow tang, I bought a Sulfur dentrifier to allow me to feed enough to keep a few fish in the tank and keep the nitrates low enough to have a few corals too.
Sulfur denitrifiers bring their own problems and I am currently struggling with pH (I think it is 8.4 right now) and Total Alkalinity (which I believe is low, but I have tried so many tests, I don't even know what unit it is measured in. I just know I am getting a change at 6 drops and it shouldn't change until 8 or 10).

I also believe I am losing snails, but I don't know if that is a natural thing, or because of something in the water I am not testing for...

Oh, Nitrates are about 1, spgr is 1.025 and temp is 79.8 or so. I have a Lobster you never see. a Coral Banded shrimp, a Maroon Clown, Yellow Tang, watchman gobi, Bicolor Blennie and a brittle star. Lots of LR A remora pro skimmer and a 20 gallon sump. About 5 maxijets and 2 Koralia 1s moving water.

LFS assures me I am not over feeding (about 1 1/2 cubes of frozen a day mostly spot feeding directly in front of the fish and watching them eat it. I also put about 3 sq inches of nori on a clip for the tang.

Tony

Oh, yeah, I keep getting cyano on the rocks and the sand?!?
I was treating it with chemiclean about 2 days before my weekly 12 gallon water change (I did that for 3 weeks), but the lfs said that might be killing some beneficial critters, so I reverted to physically removing a thin layer of diatom and sand and cyano this last water change. It is still on the rocks (cyano and brown diatom), but the overall appearance is better.

T

 

[Herefishyfishy]

Have you tried water changes?
I am not very familiar with denitrifiers but I thought that they created lower PH and acted as a calcium reactor of sorts due to the aragonite buffer. High PH and low Dkh?

 

[DonW]

You will get low ph if your not using the denitrifier properly. The cyano is of course high nutrients and more likely than not a lack of flow. I would suggest getting some test kits that are at least close and testing the tank, it does no good just to guess.

Don

 

[packer]

Yes, denitrifiers will lower your ph so that is not your problem. Also they do not affect alkalinity. If your kit is API than your alkalinity is very low at six drops. Denitrifiers use Ca media to buffer up the ph of the effluent and in turn add a bit of calcium but not enough to really make a benefit to the tank if anything is using up some calcium.

I would bet you have phosphate issues causing your cyno growth.

 

[Herefishyfishy]

How would the sulfur media acidic output dissolving the aragonite buffer material deplete calcium? I have a friend using denitrifier in lieu of water changes, whose calcium is always high solely due to the reactor.

Anyway, seems we are all in agreement that you need better test kits and possibly water changes as the high PH reading is NOT due to the reactor and there has been no accurate DKH reading completed. A denitrifier need some pretty good tests to get and keep them working correctly

 

[DonW]

How would the sulfur media acidic output dissolving the aragonite buffer material deplete calcium? I have a friend using denitrifier in lieu of water changes, whose calcium is always high solely due to the reactor.

In a fish only or a system with low ca and alk demand the denitrifier will as you stated increase both ca and alk. The fix for this is just increasing the reactors ph or using a harder media.

Don

 

[packer]

It does not deplete calcium. The ph in a denitrifier is not as low as a calcium reactor on a general basis. So the disolved amount of calcium is not as high as with a CA reactor. It does put out a small amount but if you have even a few corals with a need for calcium, the amount it puts out will not supply/keep up with that demand.

 

[Herefishyfishy]

Sorry Packer, I had misread what you had written.

 

[DonW]

It does not deplete calcium. The ph in a denitrifier is not as low as a calcium reactor on a general basis. So the disolved amount of calcium is not as high as with a CA reactor. It does put out a small amount but if you have even a few corals with a need for calcium, the amount it puts out will not supply/keep up with that demand.

Not really. If your running a denitrifier properly they can actually maintain the ca and alk of a fairly packed small sps system. With just a middle of the road of neg. -170 redox a ph of 6.5 is about what you will end up with. If you want to push it up to the max of -240 redox you can get an even lower ph. Depending on the demand and media used you can easily overshoot the parameter in a low demand system. Alot of folks do this by accident by not knowing the redox vs just measuring nitrates with a hobbiest test kit.
You can get better control over any denitrate filter by using a modified pinpoint orp controller. Chances are pretty good that if you use arm and are not burning through it at a fairly quick rate that your redox is rising above -100.

Don

 

[aaparkr]

Well here are a few details to address some of the things I read in the responses (thank you to everyone for responding!)

I do 12 gallon water changes once a week. I change with Instant Ocean that I mix in a 20 gallon tank in the same room as the 75 (right next to it). I let it age for a week with a maxijet circulating it at room temp.

The denitrifier is a Midwest Aquatics sulfur denitrifier. I don't remember the size, but it handles my tank with no problem. It initially lowered my pH significantly and my total Alkalinity because of the CO2 in the output. I wasn't aerating it nearly enough, but I have since added a small cup and an airstone to take care of the carbon dioxide and it seems to have been taken care of. Before I did that, I tried kalkwasser to raise the pH, but this is a better way. Now the Ph may be a little higher than I would like. (it does all that in the sump)

I have heard that a denitrifier will add calcium to the system and that is fine with me since I don't add calcium any other way(besides the 12 gallon water changes), but it would be a by-product. My motivation for using a denitrifier is to lower nitrates to the point that I can keep a few simple corals even though I over feed a bit because of an unusual fish load.

What strikes me as unusual is the onset of cyano over the last few months. I have been running the denitifier since April of 2007. I have 4 Maxijet 1200s running through wavemaker controllers and 2 koralia 1s running all the time. I have a sump which pulls water out of one side of the tank and returns it on the other end at whatever rate a MAG 5 runs and I have a mag 3 on a Remora Pro protein skimmer.

Tony

 

[aaparkr]

Oh I forgot, I make my own RODI water. I have a double 3 stage kent setup with 2 sediment and 1 carbon going to a RO. Both of those dump into a large DI unit with is monitored for TDS at in and out (typically 20 in and 0 out). I change the filters at least every 6 months. I change the RO once a year and The DI whenever I get greater than 3 on the output.

I was using salifert test kits for nitrates and magnesium and Alkalinity until I couldn't get the salifert alkalinity kit locally. lfs swears by the IO test, but I can't get it to agree with salifert. I guess I can order kits on line, but what do you recommend as a good basic set of tests to have. I have a refractometer, a pH meter, Salifert Nitrates, and ???

Tony

 

[deverne]

I don't remember seeing in the posts, how old are the T5 lights? I am new to the reef side of the hobby, and when I got involved I picked up a 120gal with 48" pc and halide fixture that had been in use for 4 or so months. All was going well for 6 months, and then I was getting the red slime algae. It went away when I changed the actinic bulbs. I had been maually siphoning it out with airline tubing before the bulb change. I don't know if it was coincidental or not. I know that T5's last longer than pc's, but I just wanted to mention it.

DeVerne

 

[packer]

I would also say maybe lights and what about phosphate? You dont mention any means of phosphate removal except for skimming.

 

[aaparkr]

The lights are T5s, 14 months old - supposed to last 2 years according to the LFS and the manufacturer. Installed Dec of 06.
I'd get new bulbs if someone said that would fix it. I as just going on the rated longevity.


Here are tests out of my logs with a seatest (Instant Ocean) Phosphate test
1/29/06 phosphates tested 0
12/3/07 phosphates tested 0
12/17/07 phosphates tested 0

Probably need to get a new test kit for accurate results, but I never got anything in the past.

I'm still hoping to get recommendations on a fairly comprehensive set of tests. My quarantine tank (with no fish, just a few corals) is doing well. I don't know what is different between the 2.

I just hate to go to Premium Aquatics and ask what they recommend for fear of getting loaded up with lots of stuff I don't need, but I know I need more than what I am testing now, which is spgr, temp, nitrates, pH, TA and calcium (sometimes).

Just ordered a phosphate test. I will let you know in a few days.


Tony

 

[aaparkr]

Well, a different LFS said 1 year on the lights, so maybe the initial 2 year statement was ummm, hype. Anyway, changed the lights today. Hope to see less cyano soon. I'll let you know

T

 

[aaparkr]

Resolved

It was the lights. After 2 days under new lights, the cyano is retreating. No new outbreaks and the existing ones are smaller.

Thank you everyone for your attention and responses. I guess 2 years was a bit optimistic on even T5s. Once a year is a better timetable for me anyway.

Still don't have the phosphate test and I don't know what introduces phosphates. I just seem to remember that mine are historically low.

Tony