20gh water movement ?

[the deacon]

Hello all,

I've been coasting through here for about a week and this is a great community, congrats.

I've had a freshwater set up for many years and am making the jump to marine. I am planning on starting simple but definately getting to SPS some day.

I have a 20g h and a CSL pc 2x65 watt hood and an aquaclear 201 (126gl/h), so far. I am planning on getting another 201 and heater along with 25# lr and 20#ls. I am hopeing to go the all bio filtration method, no skimmer, no mechanical filter.

My question is, with this type of system will I be getting enough oxygenation? and how can I achieve the best gas exchange with an all bio tank? What would be the opitimal position and number of powerheads for this size tank?

Thanks for all the help

[Physh1]

Sounds like your plan will be fine. As long as you don't close off the top of the tank and you have some mild surface agitation you'll have sufficient gas exchange.

 

Cameron

[the deacon]

surface agitation via a powerhead? what about salt creep?

 

deacon

[Physh1]

Salt creep is usually from excess surface aggitation. You only want to see mild ripples for it to be efficient...any more than subtle ripples is excessive and will create a lot more creep. Subtle aggitation will cause minimal creep if any.

 

Cameron

[Aiptasia]

I've got two 20g. high reefs that are similar to the design you're tring to make. Here's what i'd suggest:

 

Upping the strength of the powerheads. I've got a pair of hagen 802's in mine set up in a loop on opposite ends of the tank. I also have them hooked up to a wavemaster so they mimic ocean currents a little more closely, but this isn't absolutely necessary as long as there are no dead water zones in the tank.

 

Adding a skimmer. Believe me, if you're going to stock the tank with corals, fish and mobile inverts, you're going to need to feed them a couple of times a week. A small skimmer will really help remove DOC from the tank an hour or so after a feeding. I highly recommend adding one, the benefits far outweigh the negatives. I'd recommend a Prizm deluxe unit, or a aqua-c Remora or a CPR bakpak II reef ready. Just make sure it has a surface overflow cup. My tanks use Prizms. Skimmers also help oxygenate the water and free up CO2 when they skim.

 

I have the exact same coralife aqualights over my tanks, but I don't use the leg mounting kit. I have glass canopies on the tops of each tank and the dimensions of the light are so that I can just place them right over the canopy. This gets the light 4-6" closer to the tops of the corals, which is important with CF lights because of the PAR falloff associated with all flourescent tubes. The light comes with a 10,000k and a 20,000k bulb, but i've removed my 10,000k bulb in favor of a 50/50 bulb, so i'm running 75% actinic, 25% daylight. The corals really seem to appreciate the bluer light, especially corraline algae. Corraline algaes do much better under actinics. Even so, your tank will do fine with the bulbs included.

 

This amount of light is sufficient for most deep to mid water corals provided they are allowed to acclimate to the tank first. There are a few deep to mid water SPS corals that will do o.k. under this light, but if you want to keep the neon colored acroperas, pocillioporas, etc. you need stronger light, and definitely stronger current. There are some 175-250 watt MH/actinic hoods that will fit over the tank. Won brothers makes good ones. Those much more intense lights will allow you to keep the really bright SPS corals and such inverts as T. maxxima or T. crocea clams.

 

If you decide to keep the lights you have, you'll do fine with hardy deep to mid water corals. Mine have: Leathers, fox coral, green striped zooanthus, bubble corals, favia (brain) coral, rhodactus, ricordea, discosoma and green milliopora. If you decide not to do SPS corals, you can also add some fast growing DOC algaes, such as Caulerpa spp. or penecillium paintbrush algae to the tank. These algaes grow fast and use up a lot of DOC before it reaches the nitrogen cycle, and can be pruned back weekly, thus removing DOC from your tank (nutrient export!).

 

Salt creep happens, it's a fact of life. Just wipe the tank down with a paper towel and fresh water once a week or so.

 

Other than that, your setup sounds fine.

[Roadrunner]

Originally posted by Aiptasia

Adding a skimmer. Believe me, if you're going to stock the tank with corals, fish and mobile inverts, you're going to need to feed them a couple of times a week. A small skimmer will really help remove DOC from the tank an hour or so after a feeding. I highly recommend adding one, the benefits far outweigh the negatives. I'd recommend a Prizm deluxe unit, or a aqua-c Remora or a CPR bakpak II reef ready. Just make sure it has a surface overflow cup. My tanks use Prizms. Skimmers also help oxygenate the water and free up CO2 when they skim.

 

As in I do not have my skimmer turned on all the time?

If so why...

 

"the benefits far outweigh the negatives"

U explained the positive sides, what are the negative ones?

 

thx in advance

[the deacon]

thanks for the great info aiptasia. the powerhead upgrade sounds like a good idea. I will also check into the skimmers and see what's shake'n.

 

I would love to get a MH hood but with my current funds and lack of knowlege I might be better off starting with the custom sea life hood. Maybe i'll modifiy it later on with MH. I saw a great modification thread on here using my same hood. at least it gives me something to work towards. Its no fun if i'm set for life with one foul swoop.

 

Do you have your powerheads set at varied depth to give a more varied current coverage?

 

thanks again for the great info.

cheers

 

the deacon

[mogurnda]

I want to second Aiptasia's comments. I have essentially the same setup. The only major difference is that I don't use a glass lid, but evaporation is not measurably worse than when I had a lid. The Corallife fixtures have an acrylic lens, so I didn't want to have too many layers between the light and the livestock.

 

As far as the livestock you can keep, I also agree with Aiptasia, but would add that I am getting excellent growth with Montipora (both digitata and capricornis), one of the "easy" SPSs. In fact, the capricornis will need to be fragged regularly to keep it from taking over.

 

For circulation, I like a closed loop, because it keeps clutter and heat out of the tank. Mine runs about 500 gph. That sounds like a lot, but I wouldn't mind more. The digitata loves the current.

 

One a tank of this size, going skimmerless seems like a bad idea. I have had the venturi clog for a week on the BakPak that's on my 20 (always happens when you're out of town!), and had the NO3 go up measurably. I have the skimmer on a timer, so that it's off for a few hours after lights out, when the shrimp, crabs and clownfish larvae tend to hatch out. That way the larvae can get eaten rather than skimmed.

[the deacon]

hey dave,

what do you mean by a closed loop pertaining to circulation? and how does this help with clutter and heat?

 

cheers

deacon

[mogurnda]

I use an external pump, rather than powerheads. The system is a u-tube leading from the tank to a Mag5 pump. The output of the pump goes to a SCWD wavemaker that alternates between two outputs, generating surge.

It's a little more hassle to set up than a few powerheads, but it cuts down on clutter, and the heat from the pump vents mostly into the room rather than the tank.