Algae Scrubber for Fresh Water set up.

[whiz_bit]

Hi All,

I came across this site a couple of weeks ago and since then have been very interested in trying an algae scrubber myself. I live in a part of the UK where the tap water is hard with a rather high PH (7.8), so I have have decided to go down the African cichlid route as my tap water suits there requirements nicely. The main problem I have with the tap water is it comes out of the tap with a nitrate reading of 40mg/l which makes keeping the nitrates under control in the tank a bit of hassle. Hence liking the idea of the algae scrubber.

The tank itself is a 180l set up with Fluval 205 canister filter doing all the work. As far as I understand I would need to keep the canister filter running and run the algae scrubber in addition hopefully controlling the nitrates. Water changes which still be required to refresh the water but only about 10% a week, instead of the 20-30% a week I am currently doing. Does anyone have any experience running this things on fresh water set ups and know what sort of performance I should be looking for? Most of the designs I am have looked at run off the sump on a marine set up, can anyone point me in the right direction when there is no sump in the set up?

Thanks in advance for any advice.

Wayne

[SantaMonica]

Many folks are running FW. As long as you are not trying to keep plants, you are ok.

No more waterchanges will be needed; a scrubber does what the waterchanges did. Thus, you eliminate your nitrate/tap problem. But, if you want to continue waterchanges, 40 nitrate from the tap is pretty high. Make your scrubber strong, at 1.0 real watts per gallon.

Here is sumpless:

[Rumpy Pumpy]

Your situation sounds very similar to mine.

Freshwater, cichids, hard water area that comes out of the tap at 40 nitrates.

I do have a sump though and attempted to construct a scrubber in that last year

(see here viewtopic.php?f=3&t=162 )

Ultimately it was not successful in significantly reducing nitrate and I abandoned it.

I feel that algae scrubbers are not as effective for FW as they are for SW aquariums, although there have been some successes reported here and elsewhere, because the type of algae that grows in freshwater is not as good at fixing nitrogen as the saltwater macro algaes are (I'm sure others will disagree on that and I have no scientific basis for that claim so I stand to be corrected, but that is the feeling I have, having tried it)

That said, my attempt was limited by the amount of space that I have available in my sump. If you decide to give it a go I would suggest that you might try (assuming you have the space) using a larger screen size than most reefers use so you have more area to grow the (what I perceive to be) less effective FW algae.

I've tried a couple of other methods of reducing nitrate including two attempts at coil denitrators (both of which worked to some degree but nowhere near effectively enough) and have now settled for using two products by Seachem, "Denitrate" and "Purigen", coupled with water changes (10%/week). This is working well so far.

For your information, the "Denitrate" appears to be just crushed pumice stone (or a similar material). I have that in a canister filter with a flow of around 150 litres/hour. The recommended amount for my tank size (250 litres including the sump volume) is 500 ml but I bought 2 litres of it and put it all in the canister (my nitrates were high due to big messy eating cichlids) The idea is that aerobic and anaeobic bacteria colonise the media with the aerobic bacteria coating the outer layer of the granuals and anaerobic (denitrating) bacteria establishing deeper inside (the material is very porous). You have to keep the water flow rate quite low in order to allow this to happen. I used this on it's own for a month or so and there was a significant fall in nitrates (from over 80 to 20ish)

The Purigen is very good. The manufacturer says it works by absorbing dissolved organic material from the water, before it can be converted to ammonia, nitrite and finally nitrates. Again, I use more than the recommended amount (250ml instead of 100ml). My tank water was quite yellow when I put it in (I had been holding off the water changes to gauge how well the denitrate was performing), but within 24 hours it was crystal clear. I reckon it's worth using it just for that. My nitrates have fallen further since adding the Purigen (two weeks ago) and currently tests at about 5. The Purigen is rechargeable by treating overnight in bleach and then rinsing and dechlorinating (I haven't had to do that yet). It changes colour as it adsorbs waste, starting off yellow and ending up, I am told, dark brown. The manufacturer claims it's good for up to six months between recharges and judging from the amount that mine has changed so far (not much) I'd say that may be a valid claim.

Of course, these products, while reducing nitrate and other nasties, aren't going to remove phosphate and probably a few other things (I'm no expert) so you still need water changes to some degree.

Just my thoughts and experiences, good luck if you decide to go the scrubber route (personally I would have preferred that method if I could have made it work for me).

[SantaMonica]

From what I recall you had built a non-vertical scrubber, with a single bulb (after having tried LED's). Non-verticals have since been diagnosed as not very effective, and hard to fine tune, for a the same size vertical. This is because of the slower flow, and the algae-islands that block flow. Also, as I posted above, if 40 nitrates are going into the tank, it would be recommended to have a very strong scrubber using 1.0 watts per gal of T5HO bulbs. Looking back, I can see how your scrubber could not reduce N, since it had so many things working against it (low flow, low light power, light focusing, algae islands). Non-verticals can indeed be made to be stronger, but they have to be much bigger in size.

In contrast, the FW verticals have worked great, just so long as they are built/operated correctly (in other words, just like SW).

[Rumpy Pumpy]

Yes, it was a sloping one rather than a vertical one. Not horizontal though. The early flow issue was resolved with a bigger pump. One bulb yes, but it was a big 'un! (I didn't try LEDs by the way, but did consider it)

The main problem I think was the size. I could only fit a relatively small screen in the space I have available and while the suggestion was that it would have been big enough for a similarly sized SW tank, it certainly wasn't big enough to significantly reduce nitrate in my FW setup.

Looking at nature, the types of algae that you see growing at the shoreline in the sea are very different to those you get in FW lakes and rivers. As far as I know you can't grow "turf" in FW so you're limited to hair algae and suchlike which I don't reckon can remove as much NO3 per square inch as turf.

That said, it wasn't a wasted exercise. I learned a lot and there were some beneficial results (the algae in the tank and on the glass was reduced and became much easier to clean for one). If I had more room or if I was going to switch to saltwater (which I am considering) then I'd certainly have another go at it.

[SantaMonica]

Hair algae is actually what you want; it filters the best.

As far as the ocean, the stuff on the shore doesn't do anything. It's the thousands of cubic miles of planktonic algae which does all the filtering, and feeding, for the entire ocean.

[whiz_bit]

Hi Guys,

Thanks for the replies certainly gives me something to think about. RP I will certainly take a look at the products you suggest, they do certainly sound like an option if I decide against the scrubber route.

SM the idea that I will not need to do water changes just maintain the scrubber once a week is certainly interesting, the deign you show puts the scrubber above the tank draining back in the tank. Which I can see would be fairly easy to setup, unfortunately I don't thin my other half will let me put a scrubber on the shelf above the tank (tank is in the main living area). If I wanted to put the scrubber under the tank I am guessing I would need 2 pumps one to pump the water over the scrubber, the second to pump the water back to the tank. How do I protect myself if one pump was to fail?

So I would be looking in the region of a screen which is 5 inches wide and 10 inches high with 25w of light on each side.

I do have some plants in the tank (One corner of the tank is planted) would running the scrubber ruin these?

Thanks

Wayne

[Rumpy Pumpy]

I am guessing I would need 2 pumps one to pump the water over the scrubber, the second to pump the water back to the tank. How do I protect myself if one pump was to fail?

You don't. You use a weir or overflow box

Either one that hangs on the back like this http://bit.ly/ch1Njx

or one that has a hole though the glass like these http://bit.ly/9XvH9u (I recommend these guys by the way. I have one of their overflows and it is really good, and they supplied the correct sized hole saw to cut the hole too)

[SantaMonica]

Whiz you don't need two pumps... just use the overflow to feed the screen, and then use one pump to go back to the display. But, this setup will make more noise, light up the room more, and filter less, than an acrylic one that you can have made at your local acrylic shop using the plans I posted. Then you just set on top and be done.

A scrubber probably would starve your plants.

Here is how to do the overflow sizing:

Screen Width-----Gallons Per Hour (GPH)

1" 35
2" 70
3" 105
4" 140
5" 175
6" 210
7" 245
8" 280
9" 315
10" 350
11" 385
12" 420
13" 455
14" 490
15" 525
16" 560
17" 595
18" 630
19" 665
20" 700


If you are doing an overflow feed, the overflow will determine how much flow you have to work with. You have to start from there, and size your screen accordingly. The maximum flow you'll get to the screen will be what's going through your overflow now. This is easy to figure out by counting how many seconds it takes your overflow to fill a one-gallon jug:

60 seconds = 60 gph
30 seconds = 120 gph
15 seconds = 240 gph
10 seconds = 360 gph
8 seconds = 450 gph
5 seconds = 720 gph


Take this gph number that you end up with, and divide by 35, to get the number of inches wide the screen should be. For example, if your overflow was 240 gph, then divide this by 35 to get 6.8 (or just say 7) inches. So your screen should be 7 inches wide.

How tall should the screen it be? That is determined by how much screen area you need, which is determined by how many gallons you have. Try to get one square inch of screen (lit both sides) for every gallon. If lit on only one side, double the screen area.

When finished, this is how you want your flow to look:





Quick guidelines:

0.5 actual (not equivalent) fluorescent watts per gallon MINIMUM.
1.0 actual (not equivalent) fluorescent watts per gallon for HIGH filtering.
1.0 square inches of screen per gallon, with bulbs on BOTH sides. (10 x 10 = 100 square inches = 100 gal)
2.0 square inches of screen per gallon, if ONE sided.
18 hours of lights ON, and 6 hours of lights OFF, each day.
Flow is 24 hours, and is 35 gph per inch of width of screen, EVEN IF one sided.
Very rough screen made of roughed-up-like-a-cactus plastic canvas.
Clean algae off of screen every SEVEN (7) days NO MATTER WHAT YOU THINK.