Growing Macro Algae & A Rust Problem 3/23/09
Thanks for your help in the past.
<You're welcome and hello Sean.>
I have a few more questions. My setup is as follows: 220g display tank, 35g acrylic refugium, 25g acrylic sump, 64g Rubbermaid overflow sump, Aqua-C EV240 skimmer, polyfilter, 300lbs LR.
<Wowsie.>
I recently got some Gracilaria to grow in my acrylic sump as a macro algae filter and as a source of food for my tangs. My problem is in trying to keep it contained in the sump. Water exits the Gracilaria compartment by flowing over a baffle into a second compartment for the skimmer and poly filter. The Gracilaria wants to flow over the baffle if I let it tumble freely. I tried using a sponge to keep the Gracilaria from going over the baffle, but then much of it got caught on the sponge. So I tried using a light duty power head to constantly blow the Gracilaria off the sponge, but then the Gracilaria got pulled into the powerhead. For now, I have it sitting in a floating colander in the sump, but that prevents it from tumbling and prevents light from reaching most of it. What do you recommend to keep it in the sump while letting it tumble freely? Also, is a 24w (6700k) daylight compact fluorescent light about the right amount of light for the Gracilaria in this setup? (The Gracilaria compartment is about 12g.)
<I think I'd try cementing four PVC legs to a piece of white plastic eggcrate. Cut the legs so the eggcrate would be just below the baffle. If the eggcrate tends to float, a small piece of live rock will keep it down.>
I also got some Ulva for my refugium to (1) provide a breeding place for 'pods, (2) serve as an additional macro algae filter and (3) provide another source of food for my tangs. It's a 35g acrylic refugium, but the refugium compartment is 22" x 14" and the water level is 8" high.
It also contains LR rubble and a mixture of sand and mud. Is a 13w (6700k) daylight compact fluorescent light about the right amount of light for the Ulva in this setup?
<I'd say a little on the weak side with the length of the refugium. Adding another light and spacing out equally should give you plenty of light.>
The fuge and the acrylic sump are side-by-side, and I am running the lights for both on the same 12-hour cycle, opposite of the display tank. Also, is it correct to let the Ulva spread out over much of the water in the fuge, rather than being clumped in a ball or tumbling?
<Ulva lactuca (Sea Lettuce) normally shoots out a holdfast and if live rock rubble is present, it should attach as long as the water flow isn't too harsh.
If you prefer just using the sand bed with no rubble, I'd let the Ulva do what it wants.>
Water overflows from my display tank and is sent either to the acrylic sump or to the refugium -- so that both the Gracilaria and the Ulva get nutrient rich water -- and then flows into the overflow sump for return to the display. I have the Gracilaria and the Ulva separated so that they don't compete with each other.
<As long as they are in the same water system, there can/will be competition for nutrients.>
The display tank overflow is rated at up to 1400 gph total. I have about 1/4 of the display tank overflow water going through the refugium and about 3/4 through the sump. I have the lower flow in the refugium to provide a peaceful breeding ground for various critters and to keep the sand/mud from getting stirred up too much. Does the flow split sound appropriate for the Gracilaria and the Ulva? It sounds like the flow might be too much for the fuge, but it seems fairly peaceful in there.
<I'd leave as is.>
As a side note, I am thinking about adding a DSB in the sump compartment with the Gracilaria. My real concern there is making sure that the flow doesn't create a sand storm while letting the Gracilaria tumble.
<I wouldn't add a DSB, with the AquaC skimmer and refugium, you should be fine.>
What's your opinion on the carbon debate? Given the two macro algaes, the poly filter and the skimmer, is there much value in using carbon in this setup?
<Likely not, as long as the nutrients are being exported faster than they are imported. Keep an eye on the nitrate level.>
On another issue, I recently had a custom canopy built for my tank.
Every morning, there is so much moisture that the hinges are rusting, and I'm concerned that the rust will drip into the water and kill my fish. It's an island display, so all four sides are enclosed.
Unfortunately, I think that switching the hinges may be an expensive option (based on the way it's constructed, it may require some major re-work), and I'm not sure that any hinge would resist that much moisture anyway. As an alternative, do you think that installing a fan and a vent would take out enough moisture to solve the problem?
<I think so, and I would leave the fan run about 30 minutes after the lights go off.>
Lastly, I was having a major problem with micro bubbles due to all the turbulence in my sump/refugium setup (which is in the basement below the tank). I found a lot of suggestions in your FAQs that helped me to eliminate most of them; however, I still get a small amount. Do I need to eliminate micro bubbles completely, or is a small amount OK?
<What is a small amount, are they near the surface? Back in my early years in this hobby when horses were your ride (just kidding), there were no sumps, refugiums, and wet/dries. Biological filtration was carried out with undergravel filters employing one or more one inch lift tubes with limewood airstones powered by a Silent Giant air pump. We had tons of micro bubbles at the surface but they did not cause any harm to the inhabitants, just created a mess.>
Thanks again.
<You're welcome. James (Salty Dog)>
Sean

Re: Growing Macro Algae & A Rust Problem 3/24/09
Thanks for the fast and VERY helpful reply!
<You're welcome.>
Two quick follow-ups:
You suggested doubling the light for the Ulva refugium (from 13w to 26w). Is 24w sufficient for the Gracilaria sump, or should I increase that too?
<Depends on how far the light will be from the surface of the water and the water depth of the sump. Makes it difficult to answer without seeing your set-up. If it has good growth now, you should be fine.>
Regarding the micro bubbles, it's hard to quantify how many there are.  Before I made adjustments, it was like a swarm. Now it's just some tiny, lazy bubbles floating around spaced fairly well apart. The bubbles are so tiny that they look more like dust particles than bubbles. They are throughout the tank water (at least in the top half of the tank). There are no bubbles sitting on the surface of the water.  Should I be concerned?
<I don't like bubbles in the tank for aesthetic reasons, if you're OK with that, then no cause for concern.>
Thanks again for the info, and for all the great WWM FAQs and articles that have provided wonderful guidance to me as I dive deeper into this hobby (and my wallet!).
<You're welcome. James (Salty Dog)>
Sean