New Tank, Some Questions

[hiseabird]

Aloha everyone, I've been avidly reading these discussion threads and have found them extremely helpful! I recently set up an opae'ula tank and have a few questions I was hoping to get some thoughts on ...

I have a fair amount of brown algae growing on the sides of the tank and getting worse. I know that's common for young tanks, but I also read that the shrimp don't eat it very much?

1. Should I NOT put the tank under a direct full-spectrum light but instead just use a LED aquarium light to prevent excessive algae growth that the shrimp won't keep up with?
2. Should I leave the brown algae/diatoms all over the tank sides as is and hope it goes away eventually, or wipe it off?

My setup:
- 2.7 gal Penn Plax Vertex glass fish/shrimp tank (with lightweight plastic lid that covers most of the top but leaves a gap)
- Heavily cleaned fine sand from Lanikai Beach on Oahu (primarily calcium carbonate)
- Dead coral piece found on a beach on Lanai (where I live now; cleaned, soaked, rinsed, etc.)
- 1/2 salinity water using RO water and Instant Ocean marine salt (ended up with SG at 1.009-1.01)
- Let tank sit for a few days
- Macroalgae and algae ball arrived from Mustafa and we added those
- Let sit for another 2+ weeks next to a full-spectrum desk light during the day
- Saw bunches of algae growth (mostly brown I guess) with a biofilm that was catching lots of bubbles (I presume bubbles created by the diatoms)
- Ordered shrimp and added them a few days ago

The shrimp all ran around like crazy for about a day exploring all the holes in the coral rock, moving sand around, and picking up algae from the surface biofilm and tank sides. Of the 30 we got, we could see ~20 of them at any given time. Since day 2 (like many people have observed), they totally chilled out and are mostly hiding (only seeing ~15 at a time), though I can see them moving around in the coral rock caves and holes.

I've been wanting some 'opae'ula for years and these are just awesome. They arrived all the way to Hawaii alive and happy, and I can feel good (as a conservation biologist) that they were not wild-caught. Mustafa - do you know the origin of your breeding colony? I love the stories of where all the animals in my family came from. These little guys make me so ridiculously happy and are so calming to watch. Thank you and I'm looking forward to watching them shrimp around and hopefully have shrimp babies someday.

Thanks in advance for your help!
- Rachel

[KenCotigirl]

Adding my two cents.

1. I do not believe the type of light is that important. Duration and intensity is the issue. If you feel there is too much algae growth just keep the light on for an hour or so in the morning and several hours after work till bedtime. If you want to use LED light get a light that is dimmable. That way you can leave the light on longer by dimming the light.

2. I would leave the growth on all sides but the front. Did I miss it you your post. Did you get snails? Mustafa's snails help clean the glass.

Ken

[Mustafa]

Hi Rachel!

Thanks for the detailed write-up! As Ken said, the brackish water snails *love* the brown algae and usually eliminate it after a while. Depending on your nutrient levels you will probably still have green algae growing which you can clean or leave as you wish. I kinda do what Ken does...I clean the front glass and let the algae grow elsewhere, but you can elect to clean it on all sides of the tank. It certainly won't harm the shrimp and they will munch on the cleaned off algae.

As for light...doesn't really matter either way. I don't use light to control algae. The best way to "control" algae is via added nutrients (i.e. amount of food) and hand-cleaning. What you can do is simply not feed until the algae are pretty much gone. The macroalgae will compete with the microalgae and help eliminate the nutrients that promote algae growth. The shrimp and snails (if you get them) will be totally fine. There is plenty of food there as long as you see algae. A member here has been running a tank for over 4 years without feeding once and his shrimp aren't only healthy but also reproducing. As an added "side effect" you'll see a whole lot more shrimp out in the open looking for food once the amount of visible algae decreases. Right now they're not moving much because they don't have to. They literally have to just pick around where they are and there is already plenty of food.

As for the source of the original Opae...according to Scott Santos from Auburn University who performed genetic analyses on various Opae ula/Halocaridina rubra populations on the Hawaiian islands my population is most likely from the Kona coast of the big Island.

[hiseabird]

Thank you both so much! I was debating, but may get some snails after all. I was thinking about making a 1 gallon tank for my office (so I can enjoy 'opae'ula all day at work and at home). So perhaps I could put most of the snails in the big tank, but a few of the snails in the 1 gal and move maybe 5 of the 30 shrimp that are currently in the big tank.

Thank you!

Aloha,
Rachel

[Mustafa]

Sure, that sounds like a viable idea. Although, I'd probably move 10 shrimp so you can see more of them at a time in the small tank.

[hiseabird]

Update (and question): To review, I started with 30 shrimp, and 10 snails in January. I've got berried shrimp! Noticed the first in early May. I think I got up to 5 or 6 berried. I saw the first larvae on May 30. Now there are a few tiny shrimp, and I think 2-3 more have released larvae, with at least 3 left to go. I am so excited!

I do still end up with what seems like way too much algae on the glass (mostly green-ish in blotches and streaks, with some general growth that makes the glass cloudy). - I scrape off with a (clean) toothbrush occasionally so I can see my beloved opae - maybe cleaned the glass 3 times since January? Not sure if it's getting too much or too little light, or if that's just a function of the warm weather here in Hawaii. I've got some macroalgae doing great in there too and just noticed a baby snail yesterday! It's only about 2mm long. Haven't noticed any others yet, but I assume there will be more at some point.

But now I have a potential issue ... it looks like there are tiny, white, writhing worms in the tank (~1-2 dozen of them, smaller than the opae larvae). Could they be mosquito larvae?? (I live in Hawaii.) Mostly hanging out near the surface. I can't get my phone to focus on them to take a photo. Help! Has anyone else had tiny wigglies in their tanks? Is there any way to get rid of them without harming my shrimps?

[hiseabird]

Two photos of the setup, berried shrimp, and algae (still cannot get photos of the tiny white worms/larvae).

[Varanus]

According to wikipedia at least, no mosquito species' larva can handle water that is more than one third ocean salinity, so its doubtful those are mosquito larva. But whatever they are, they'll likely die off over time provided you keep the nutrient level in the tank low (i.e. don't overfeed).

[hiseabird]

Here are two photos of the unknown wiggly animal ...

[Stalker]

Yes its mosquito, several species can breed in brackish water.

[Varanus]

Huh, guess wikipedia was wrong about how much salinity they can take (assuming your tank is half ocean salinity).

[hiseabird]

Crap-tastic. Yeah, that's what I had been thinking based on further research. Ok, so mosquitoes - I've covered the strip that the tank lid didn't originally cover. It's not air-tight, but I think it will keep out adult mosquitoes. I've ordered a small dip net with much smaller mesh (my current one won't scoop up the mosquito larvae).

Other than physically scooping, what do you think would work ... small airstone for a bit to disturb the water surface and discourage adult mosquitoes? Anything else I could add? Or do I just need to scoop them out individually? I have about 30+ opae larvae floating around too, with 3 more berried shrimp ready to release larvae in the next few weeks, so I don't want to hurt them (obviously). Any ideas? (I hate mosquitoes so much for so many reasons, this is just adding to the list.) Thank you so much for the help!

[Varanus]

If you've covered up the opening then you shouldn't have an issue with more mosquitos using the tank as a breeding site, and as for the ones in the tank already, unless you do want to scoop them out individually it may be best just to wait. Assuming the mosquito larva can complete their development, they'll probably drown once they turn into adults and have no way to escape from the tank and find food. Then you can easily scoop out the bodies from the surface film. And if they can't complete their development, the shrimp will likely dispose of the bodies.

[AnotherKevin]

You could also suck them out one at a time with a turkey baster, but it would be very tedious.

[Mustafa]

May or may not be a mosquito larva, but definitely some kind of insect/fly larva...something midge-like. How many are there and are they growing? Mosquito larvae (the ones that bite us) tend to be black by the way.