Why won't my zoanthid grow?

[Dave Clark]

Hello. I have a Fluval Evo 52l nano tank that's been running for about a year. I've had a zoanthid in the tank for maybe about 8 months, and it refuses to grow. It's not dead because it reacts to pulses of water etc., but it's tiny ... like only about 1/8" (3mm).

I've been Googling to figure out why it isn't growing, but I get a lot of conflicting information. Can anyone help me out? Tank params:

Temp: 78F / 25.6C
Flow: 1500 lph / ~300 gph through two RFG nozzles
Nitrate: 0
Phosphorus: 0
Alk: 7.7
Calcium: 415
Magnesium: 1500
pH 8.0 - 8.2
lighting: Fluval Marine 3.0 (zoa is about 10" / 25cm below light)

Thanks in advance.

 

[JNalley]

Can you take a picture of it? Preferably when fully open?


Which Nitrate and Phosphorus tests are you using? Are they the Ultra Low Range tests? Those two numbers should not be at 0. Nitrate should be at least 5-10ppm, and Phosphate (I don't have time to do the math to give you a phosphorus number) should be about 0.1

 

[areohen]

You may want to increase your nitrates. Being at 0 is not good for your corals

What's your light setting? You may need to increase the intensity

 

[Sophie"s mom]

as others have said you do not want zero for neither nitrates or phosphates. also, some zoas grow much faster than others. What type do you have? But whatever the type, they actually prefer somewhat "dirty water. By dirty I mean nitrates about 10ppm, and phosphates about .10.

 

[Dave Clark]

Can you take a picture of it? Preferably when fully open?


Which Nitrate and Phosphorus tests are you using? Are they the Ultra Low Range tests? Those two numbers should not be at 0. Nitrate should be at least 5-10ppm, and Phosphate (I don't have time to do the math to give you a phosphorus number) should be about 0.1

Sorry, this was the best I can do. It's very small.

I'm using the Hanna Checker tests. About a month ago I added chaeto to address pH issues (which worked), and then my nitrates and phosphate numbers dropped to 0 from 5 ppm and 5 ppb respectively. But the zoa was this small for months before I added the chaeto.

 

[Glenner’sreef]

So zoanthids/palythoeas depending on the strain or variety can be as small as 1/16” to the size of a quarter.

 

[Dave Clark]

You may want to increase your nitrates. Being at 0 is not good for your corals

What's your light setting? You may need to increase the intensity

What do you recommend as an ideal nitrate level for soft corals?

Re light setting, I have the lights on for 12 hours, ramping up to whites at 50% and all other colors at 100% for 6 hours. I don't know how that translates to Fluval's advertised PAR for this light, or whether their advertised PAR is accurate. According to Fluval, at 10" I should be getting a PAR of about 100.

 

[Dave Clark]

So zoanthids/palythoeas depending on the strain or variety can be as small as 1/16” to the size of a quarter.

Interesting. So I'm pretty sure this is a Dracula zoa. After first putting it into the tank, after it opened up, it was about 1/2" wide, but it's shrunk since then.

 

[Dave Clark]

as others have said you do not want zero for neither nitrates or phosphates. also, some zoas grow much faster than others. What type do you have? But whatever the type, they actually prefer somewhat "dirty water. By dirty I mean nitrates about 10ppm, and phosphates about .10.

I'm fairly sure it's a Dracula zoa. It has been this size for at least 6 months now (when it first opened up after I added it to the tank, it was about 1/2"). I've only had nitrates and phosphates at 0 for about a month, after adding chaeto.

 

[Glenner’sreef]

Interesting. So I'm pretty sure this is a Dracula zoa. After first putting it into the tank, I would say after it opened up, it was about 1/2" wide, but it's shrunk since then.

I'm fairly sure it's a Dracula zoa. It has been this size for at least 6 months now (when it first opened up after I added it to the tank, it was about 1/2"). I've only had nitrates and phosphates at 0 for about a month, after adding chaeto.

As you’ve heard zero with both Nitrates and Phosphates aren’t ideal. Zoas not sps and don’t mind dirtier water. Something to consider.

 

[JNalley]

Sorry, this was the best I can do. It's very small.

I'm using the Hanna Checker tests. About a month ago I added chaeto to address pH issues (which worked), and then my nitrates and phosphate numbers dropped to 0 from 5 ppm and 5 ppb respectively. But the zoa was this small for months before I added the chaeto.

yeh, that zoa looks unhappy. It's probably too much light to be honest, it's only partially opening. And I see that you've mentioned it shrunk. These are pretty clear signs that things aren't right and it isn't happy. If it was shrunk like that before adding the chaeto and reducing nitrates, I would bet it's lighting. Drop them down to 20% for the next 2-3 weeks and see how it reacts. If it opens up, start stepping the lighting up in 5% increments every week and see how it reacts to that. You may be able to get back to the same level of lighting as corals are generally adaptable, but you also may not.


Edit: You will need to do this in conjunction with raising the nitrates. I keep my tank around 20-25ppm Nitrate and 0.1 Phosphate.

 

[Dave Clark]

yeh, that zoa looks unhappy. It's probably too much light to be honest, it's only partially opening. And I see that you've mentioned it shrunk. These are pretty clear signs that things aren't right and it isn't happy. If it was shrunk like that before adding the chaeto and reducing nitrates, I would bet it's lighting. Drop them down to 20% for the next 2-3 weeks and see how it reacts. If it opens up, start stepping the lighting up in 5% increments every week and see how it reacts to that. You may be able to get back to the same level of lighting as corals are generally adaptable, but you also may not.


Edit: You will need to do this in conjunction with raising the nitrates. I keep my tank around 20-25ppm Nitrate and 0.1 Phosphate.

Thank you, will try decreasing the light. Any particular part of the spectrum ... decrease just whites, or everything?

Do you need to dose nitrate and phosphate, or does. your tank just get them from feeding?

 

[kevgib67]

My money is on that zero nitrates and phosphates is starving your zoa if your results are accurate. I think you’ll notice a difference when you get your levels up to what was mentioned above.

 

[elysics]

I'm fairly sure it's a Dracula zoa. It has been this size for at least 6 months now (when it first opened up after I added it to the tank, it was about 1/2"). I've only had nitrates and phosphates at 0 for about a month, after adding chaeto.

Shrinking zoas are starving zoas. Or sometimes to little/too much light

 

[JNalley]

Thank you, will try decreasing the light. Any particular part of the spectrum ... decrease just whites, or everything?

Do you need to dose nitrate and phosphate, or does. your tank just get them from feeding?

Decrease the entire spectrum. The best way to tackle lights is to start with a spectrum you know works for the coral (Check, the Fluval 3.0 does that), Then within that spectrum, add white to taste (for your viewing), lastly, increase or decrease the entire spectrum so that intensity is correct for the corals in question.

My nitrates stay that high from me feeding my tank. If you're running relatively low nutrients (5-10ppm) and you need to correct for pH, the answer probably shouldn't be a Refugium running chaeto, because it will require what little nutrients you have to fix your pH problem. If you want to combat pH in a meaningful way, you could always try a CO2 scrubber on your skimmer, or running your skimmer using an outside airline. The other way you can tackle it is by dosing kalkwasser (though, I wouldn't recommend this method unless you're also having Alkalinity or Calcium problems).

 

[PeterEde]

Check this video for nutrient levels

 

[Dave Clark]

My money is on that zero nitrates and phosphates is starving your zoa if your results are accurate. I think you’ll notice a difference when you get your levels up to what was mentioned above.

I'd think so too except those levels have only been zero for about a month now. For about 7 months before that, nitrates were typically around 5 ppm and phosphates about 10 ppb.

 

[Dave Clark]

Decrease the entire spectrum. The best way to tackle lights is to start with a spectrum you know works for the coral (Check, the Fluval 3.0 does that), Then within that spectrum, add white to taste (for your viewing), lastly, increase or decrease the entire spectrum so that intensity is correct for the corals in question.

My nitrates stay that high from me feeding my tank. If you're running relatively low nutrients (5-10ppm) and you need to correct for pH, the answer probably shouldn't be a Refugium running chaeto, because it will require what little nutrients you have to fix your pH problem. If you want to combat pH in a meaningful way, you could always try a CO2 scrubber on your skimmer, or running your skimmer using an outside airline. The other way you can tackle it is by dosing kalkwasser (though, I wouldn't recommend this method unless you're also having Alkalinity or Calcium problems).

Actually my alkalinity is been running lower than usual, after adding the chaeto. Not sure why as I've read that chaeto doesn't "use" alk.

I don't have a skimmer and don't really add one, but I do have an IceCap scrubber that I might be able to use with an air pump and an air stone. I've heard that others have had some success with that. But darn, I really like the lack of hardware with the chaeto setup. I'm wondering if I could dose nitrates, or if the chaeto would suck it all up before the corals get a chance?

Thank you.

 

[JNalley]

Actually my alkalinity is been running lower than usual, after adding the chaeto. Not sure why as I've read that chaeto doesn't "use" alk.

I don't have a skimmer and don't really add one, but I do have an IceCap scrubber that I might be able to use with an air pump and an air stone. I've heard that others have had some success with that. But darn, I really like the lack of hardware with the chaeto setup. I'm wondering if I could dose nitrates, or if the chaeto would suck it all up before the corals get a chance?

Thank you.

you can still run the fuge, you may just want to try a shorter lighting period if you can and dose some extra nitrates. Randy did a write-up on dosing ammonia sources too which convert to nitrate via your biological filtration, so that may be worth a read.


Edit: Sorry, forgot to respond to the part about the scrubber. I know a skimmer works because it's doing the most gas exchange of any of the ways an aquarium can do Gas exchange... I am not sure that an airpump/airstone (along with the CO2 Scrubber) would be sufficient enough. Someone with more knowledge of that end of things can chime in maybe...

 

[Outlaw Corals]

You have no nutrients at all your nitrates and phosphates have bottomed out and you have to be careful. Your tank doesn’t crash. Zoa’s why can’t nutrients and they like to be fed a lot.