Algae Scrubber Basics

Im new to the ats I build one like a month ago for my 75 gallon tank and I am still getting algae in the main tank. I am using 23 watt cfl 2700k bulbs on both side of the screen my screen is 12 by 13 I let the lights stay on for 16 hours a day for my ats the screen is green but I dont see any algae going on it is there are thing that I am doing wrong or should I add other 23 watt cfl to both side of the screen

 

Okay to get started your screen is way over built for you system unless you are feeding a rediculios amount of food. The 12" x 13" screen is rated for a 156 gallon tank which is not want you have you need a screen that is rated for a 75 gallon tank and at most a 100 gallon tank. So a screen that is 9" x 9" will be rated for an 81 gallon tank and should work really well for you.

The lights that you have shining on the screen now are not powerful enough for that large screen. The general rule of thumb is that for every 1" x 1" you need 1 watt of light. So the 156 sized screen you have on there now would need at least 156 watts to power it, but again this screen is to large.

So I would resize your screen to a 10" x 10" and you can still use the 23 watt bulbs but your total wattage will only be at 46 watts 1/2 of what ideal is which will get you started but the 32 watt 150w equivilants would be better.

Okay so to recap:
-Re-size your screen to 10x10 at the most.
-Increase light output 1 watt per 1 square in.
-Finally make sure you have enough flow (10x10 will need around 350gph)

If you have any questions give the very long post turbo put on in the first post a good read it should starighten anything out that you need to know if not ask away.

 

What If i was to do a single sided scrubber? For a 65 gallon display tank and 40 gallon sump. Half of the sump is full other half is half full? Dose that make sense so out of 40 gallons 30 of it is water. I use bio pellets but still get algae. And have high phos. And want to try this. So this is my question can I do a single sided one? How much screan for 95 gallons of water if I am using one side? I have a mag7 split to a fuge with verry little flow most flow is to DT this will be gravity feed. Is that enough flow? Thanks and I hope this makes sense

 

what a GREAT THREAD i have been lookin for something like this giving you a step by step on how to make 1 of these and this was right on the money. Now i can go ahead and begin to add 1 to my new upcomin system

 

You can do a single sided scrubber, they are just not as efficient as a double sided. Your DT size and sump size has nothing to do with sizing the scrubber. You size the scrubber based on how much you are feeding. Here are the guidelines, this is what 12 square inches of screen can handle, one of the following:


1 frozen cube per day (2-sided screen)
1/2 frozen cube per day (1-sided screen)
10 pinches of flake food per day (2-sided screen)
5 pinches of flake food per day (1-sided screen)
10 square inches (50 sq cm) of nori per day (2-sided screen)
5 square inches (50 sq cm) of nori per day (1-sided screen)
0.1 dry ounce (2.8 grams) of pellet food per day (2-sided screen)
0.05 dry ounce (1.4 grams) of pellet food per day (1-sided screen)


I dont really like to recommend gravity fed scrubbers. I know people are running them, but I like pump fed scrubbers better. You need 35 GPH per inch of screen width. So take screen width x 35 = how much flow you need. The reason why I dont like gravity fed scrubbers is that you are going to have to figure out how much flow you have draining back to the sump, and then you will be stuck sizing your screen according to the flow from the DT. Pump fed scrubbers allow more flexibility.

 

insanespain thanks for posting those, I was going to do that myself!

For anyone paying attention, there is a new scrubber sizing guideline based on the amount you feed. This makes sense if you think about it, because the algae will grow in proportion to the bio-load, which is driven directly by the amount of nutrients (food) introduced into the system (by way of feeding) on a daily average (over a week).

You can still use the tank size to size the scrubber, in that case just go by the DT stock size not actual gallons, unless your sump/fuge has a bio-load as well. However this is usually not the case, even if there is something in it.

Single sided screens are less efficient. Go double sided if it's at all possible. If you have to go single sided, keep the flow at 35 GPH/in, don't think you can cut it in half. Single sided needs to be 2x the dimension and have the same amount of light as double side lit.

If you use the feeding guideline sizing method, use a minimum of 1W/sq in of light. So if your screen is 7x7, or 49 sq in (4 cubes/day) you would want one 23W or 26W CFL on each side.

I haven't kept this thread well updated (been way busy) so here's another update from the Algae Scrubber site:

The above process can actually be used in any situation. Double the light and halve the photoperiod as described on a smaller screen will intensify the growth of the algae, just remember that CFLs may need to be backed off a little if they're significantly bigger.

Regarding Bio-pellets:

The scrubber won't work will with biopellets. In simplistic terms, the bacterial colony supported by biopellets consumes the nutrients before the scrubber can. If you want to try a scrubber, I suggest a long transition. Start the scrubber and let the screen get a slime coating and the starting phases of algae growth. Do this for at least a couple of weeks, maybe a month. Reduce the amount of biopellets you use for the first month by about 1/4. After a month, reduce the biopellets by another 1/4, so now you've got half of what you were running. Go another half after another month to now 1/4 of original. After 2 months you can probably take it off line.

This process ensures a smoother transition without shocking the system. If you take the biopellet reactor offline completely, all of the sudden you have a large bacterial colony with no carbon source and you will have a large die-off.

 

New Scrubber Sizing Guideline (Sept 2011)

Scrubbers will now be sized according to feeding. Nutrients "in" (feeding) must equal nutrients "out" (scrubber growth), no matter how many gallons you have. So...

An example VERTICAL waterfall screen size is 3 X 4 inches = 12 square inches of screen (7.5 X 10 cm = 75 sq cm) with a total of 12 real watts (not equivalent) of fluorescent light for 18 hours a day. If all 12 watts are on one side, it is a 1-sided screen. If 6 watts are on each side, it is a 2-sided screen, but the total is still 12 watts for 18 hours a day. This screen size and wattage should be able to handle the following amounts of daily feeding:

1 frozen cube per day (2-sided screen)
1/2 frozen cube per day (1-sided screen)
10 pinches of flake food per day (2-sided screen)
5 pinches of flake food per day (1-sided screen)
10 square inches (50 sq cm) of nori per day (2-sided screen)
5 square inches (50 sq cm) of nori per day (1-sided screen)
0.1 dry ounce (2.8 grams) of pellet food per day (2-sided screen)
0.05 dry ounce (1.4 grams) of pellet food per day (1-sided screen)

High-wattage technique: Double the wattage, and cut the hours in half (to 9 per day). This will get brown screens to grow green much faster. Thus the example above would be 12 watts on each side, for a total of 24 watts, but for only 9 hours per day. If growth starts to turn YELLOW, then increase the flow, or add iron, or reduce the number of hours. And since the bulbs are operating for 9 hours instead of 18, they will last 6 months instead of 3 months.

HORIZONTAL screens: Multiply the screen size by 4, and the wattage by 1.5

Flow is 24 hours, and is at least 35 gph per inch of width of screen [60 lph per cm], EVEN IF one sided or horizontal.

Very rough screen made of roughed-up-like-a-cactus plastic canvas.

Clean algae off of screen every 7 to 14 days, so that you can see the white screen material.

 

Hey Floyd, glad you made it over here. Your other threads are quite daunting to decide to wade in a give it all a read. I've talked with you about horizontal scrubbers, and some of the down falls to that that I had not thought of.

The thought of a algae driven nutrient export system is interesting. There are some ideas I have that I would like to try in the future. But right now, one of the problems I am having with the idea is energy consumption. The idea itself sounds great, and the benefits are good too... but when it comes to lights and pumps, and then having a well built scrubber with good lighting... as with anything, the more "powerful" scrubber uses more power.

I am having a hard time trying to figure out what is more energy efficient for nutrient export for a given size tank compared to say skimmer and bio pellets. I understand many still use skimmers... but I am thinking of a more natural setup... using a biological driven system as opposed to a "mechanical" driven system. Considering lots of LR and algae it's hard to beat the simplicity and efficiency of a skimmer and bio reactor.

What do you think about that? Any help you can provide?

 

The savings start to add up more when you size the screen according to the bio-load / feeding schedule. But you're talking costs analysis here and I don't know what specific pumps you are running.

Should be pretty simple to figure out though. If you're looking purely at energy savings versus running a skimmer, the Algae Scrubber may not win, especially if it's pump driven because that's going to be a pretty close match as far as watt useage, then you're adding the lights on top of that.

So you have to look at it from an overall budget perspective. Consider all your filtration related expenses, ignoring equipment cost:

Energy to run skimmer
Cost of currently used media per month (pellets, filter socks, etc) including necessary shipping, gas to drive to store (you needed to go there anyways though...)

Next calculate cost of running a scrubber:
Energy to for pump
Energy for lights

The factors that will drive the 2 energy requirements are
1) how big is your screen, which then determines 2 and 3
2) how big is your pump
3) how many watts of light

#3 is pretty much set based on #1 because if you choose the 9 hr photoperiod method you have to double the wattage, so it's the same daily usage. The only difference is the 9 hr method extends the time frame between needing to change the lamps.

Other factors you should probably figure in are dependent on your particular set of circumstances, such as reduction of the reliance on PWCs for nutrient reduction, local energy costs.

There are other less tangible benefits to consider as well.

Skimmers take out organics (food), while scrubbers take out inorganics (waste). I see regular recommendations to turn off pumps/skimmer during feeding, especially if you feed a DIY food with octopus in it - makes the skimmer go nuts. A scrubber will leave the food in the system for the corals/fish/inverts to actually consume and turn into waste. For instance, I have a Sun Coral (NPS) that I haven't target fed in 18 months.

All of this means your food is actually consumed in total by some part of the system, so you get more bang for the buck. The flipside of that is that scrubbers allow you to feed more, so you end up using more food because heck why not.

Seriously though people's jaws drop when I show them my tank, which has all types of corals, then I tell them how much I feed (5-10 cubes a day) and then I tell them that I do not do PWCs and N=0 P=0.09-0.16 (P won't go below that, but everything is doing fine...go figure, another hard-and-fast rule that I seem to be contradicting).

the original tank this system was in was at an office, the tank cracked, and I had to move it. Then I had a problem with the stand for the tank at my house, and I had to tear the tank down again 3 days later. One fish ate another in this whole process but other than that, everything survived stellarly. I saw no cycle as a result of removing all of the rock, much of it encrusted in sponges which surely had some death from exposure to air, nor a cycle from washing the live sand with hose water which essentially sterilized it.

So for me, it's hard to make an apples-to-apple comparison, because from my experiences, nothing even comes close.

 

Thank you very much Floyd. Exactly what I wanted...I was not trying to revisit any "this vs. that" thread.

Real quick, what is "PWC". Brain is not quite working right after 80 hours of work over the last 5 days.

When numbers are finally put to paper you can come up with a cost comparison, but you are right, it is not a apples to apples comparison. Seems to me they may give the same filtration end result... low waste nutrients, but there are other benefits provided too.

So one thing... your P is pretty high compared to the ULN crowd... but it seems to me that P by itself is not "bad". Really high may cause other problems, but on the low side... which yours is... it may or may not slow coral growth. Seems to me that these days isn't so much about how you can keep a healthy reef, but how fast you can grow a tank of SPS... sort of like hydroponics... Hydroponics does not do anything for plants... it just allows faster growth indoors. So if your tank is full and your corals are growing, then it is hard to say what rate would or would not be "better".

Have you tried other methods of reducing P to compare how things work for you? (I'm sure you have)

I have this vision of a tank I want in the future (currently tankless ). Right now, low maintenance and low operating costs are paramount. Obviously it takes what it takes, and I want a vibrant healthy reef, but minimizing those things happens on the design end not the operating end. Just doing my research into alternatives to keep me busy. Designing a biologically driven system is very interesting even to this "gear junkie" that never saw a shinny object I didn't like. ;D