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Home: KOI Talk: Pond Construction & Water Filtering System:
Why call dry/wet if dry is better?

 




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cometress
Novice

Sep 17, 2002, 7:08 AM

Post #1 of 49 (66524 views)
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Why call dry/wet if dry is better? Can't Post

After reading widely on the different types of flitration system, it appears that the trickling tower (TT) filled with bio balls is considered the best amongst all other systems to nitrify bacterias, because this syetm allows water to drip slowly through many layers of porous materails (bio balls) in a highly oxygenated environment. This TT somehow also commonly known as dry/wet system, intrigues me to examine their set-up whenever I pass by fish shops.

Most of the set-ups of such towers has the top half trickling with water and the bottom half submerged with water. So I have several questions:

1) If trickling is so effective, why they allow the bottom half to submerge with water which is erected just besides a sump which draws water back to the tank using a power head. Isn't letting the bio balls half submerge will render this system less effcetive? (The bottom level of the tower and sump are on the same plane for this case).

2) Why don't they simply erect the tower above the sump and allow all bio balls to receieve the trickling effect, thus becomes a totally dry system? OK, for commercial reason, maybe lack of space but have seen many shops are doing the same as described in (1).

3) So I ask the salesmen but none can give me a convincing answer. However, one told me we need the dry and wet to handle all different kinds of bacterials. This is perhaps the nearest convincing answer I got.

Any expert willing to elaborate?Angelic


johnson lee
Veteran

Sep 17, 2002, 8:14 AM

Post #2 of 49 (66475 views)
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Re: [cometress] Why call dry/wet if dry is better? [In reply to] Can't Post

Hi there again!Wink

The principle of a TT filter is that when water with nitrates trickles through the air and pass the bio-balls, nitrates is converted into nitrous oxide. Hence, the water going back into the pond contains very little or totally no traces of nitrates anymore. The effectiveness is the water trickling down a height of at least 12" before reaching the media. If you have a number of trays containing bio-balls, the water will still be trickling pass a dry environment until it reaches the last tray which carries the water back into the pond.

So, it doesn't matter whether the last part of the TT filter is submerged or not, the effectiveness is at the beginning of the trickle up to the next few trays of bio-balls. However, having said that, I am puzzled why should the koi keeper submerge part of the TT filter in water? It should be free standing and the last tray will flow back into the pond!

I hope this makes sense to you.

Johnson



cometress
Novice

Sep 17, 2002, 9:02 AM

Post #3 of 49 (66470 views)
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Re: [johnson lee] Why call dry/wet if dry is better? [In reply to] Can't Post

Thanks.

I read somewhere in this forum that it has to be a height of 3' for any effectiveness, whereas you mention a min. of 1'. Is there any scientific write up on this? Sorry, I'm not doubting you but I'm really keen to keep track on this. Smile


johnson lee
Veteran

Sep 17, 2002, 9:14 AM

Post #4 of 49 (66467 views)
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Re: [cometress] Why call dry/wet if dry is better? [In reply to] Can't Post

Errr....sorry no scientific and empirical evidence on this.Crazy Just through trial and error and experimenting.

If you have a height of 3' between the trickle and the media, you must make a rather tall TT filter! I believe a minimum of 1' is sufficient. Just my opinion.Smile

Johnson


cometress
Novice

Sep 17, 2002, 4:56 PM

Post #5 of 49 (66452 views)
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Re: [johnson lee] Why call dry/wet if dry is better? [In reply to] Can't Post

Johnson Lee,

Thanks for the prompt reply. Happy ponding.Sly


johnson lee
Veteran

Sep 18, 2002, 6:26 AM

Post #6 of 49 (66438 views)
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Re: [cometress] Why call dry/wet if dry is better? [In reply to] Can't Post

You're welcome and hope to see you more often on this forum!Smile

Johnson


SMW1
Veteran

Sep 18, 2002, 9:46 AM

Post #7 of 49 (66435 views)
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Re: [cometress] Why call dry/wet if dry is better? [In reply to] Can't Post

Any size TT is better than none at all Crazy.

However tall and thin is better than short and fat. The more media the water passes over during the filtration process of the TT the more nitrates are removed. Size is totally dependant on the amount of Nitrates you want to remove. i.e. a bigger pond with no vegitation will requie much taller TT than a small pond with lots of plants, which will probably need a very small one if at all.


jitwee
User

Sep 18, 2002, 5:37 PM

Post #8 of 49 (66424 views)
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Re: [SMW1] Why call dry/wet if dry is better? [In reply to] Can't Post

Hi guys,

I needed some advise from you all. I have a TT system at my last chamber. Meaning part of the water is being pumped back to my main tank and the rest is to my TT. I have being adjusting the flow rate to my TT for a few weeks but the result of my NO3 don't seem to drop ( maintain at 50ppm).

My TT dimension are :
Diameter of PVC pipe : 7 inch
Height of the TT : 32 inch inclusive of elbow.
Height of the bio ball : 20 inch
Water trickle from the pipe to bio ball : 8 inch

Is there any thing wrong with my TT setup or i still needed to wait for a while for my TT to kick in ?
If i were to look for a individual pump for my TT, what flow rate must i buy ?
Does it mean that the lesser we feed the level of the Ammonia,NO2 and NO3 will also drop since they are all link together?

Sorry for so much question,still very new to this hobbyBlush


SMW1
Veteran

Sep 18, 2002, 6:54 PM

Post #9 of 49 (66417 views)
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Re: [jitwee] Why call dry/wet if dry is better? [In reply to] Can't Post

Hi, The size of the TT and the effect it has deends on the volume of water yor pond is holding and the stock level.

What size is your pond ?.

Yes feeding less means less polution. Fish waste and rotting excess food will produce ammonia, nitrosomonas consumes ammonia producing nitrite, nitrobacter consumes nitrites producing nitrates. So if you feed less you produce less ammonia, therefore these nitro guys don't have to work so hard - simple Crazy


johnson lee
Veteran

Sep 19, 2002, 5:21 AM

Post #10 of 49 (66407 views)
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Re: [jitwee] Why call dry/wet if dry is better? [In reply to] Can't Post

Hi Jitwee

Your TT dimensions seemed fine to me. But it would be better if you can adjust to have the distance netween the trickle and the bio-balls to at least 1'. Give it a little more time and nitrates should start reducing. Of course, the less you feed , the less work your good bugs will have.

Moderation is the best policy, I'll say!Smile Best wishes.

Johnson


jitwee
User

Sep 20, 2002, 2:18 AM

Post #11 of 49 (66392 views)
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Re: [johnson lee] Why call dry/wet if dry is better? [In reply to] Can't Post

Thanks for your advise,

If my trickle distance to my bio ball increase to 1 feet,this means that the height of the bio ball will reduced to 1.5 feet. Is it ok to reduced the number of bio ball?

Can i increase the good bug by adding those liquid/power solution which is avaible in the store ?

I did a partion change of water every 2 days, will this kill away the good bugs (anti chlorine is added).

Regards,
jitwee


johnson lee
Veteran

Sep 20, 2002, 5:57 AM

Post #12 of 49 (66387 views)
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Re: [jitwee] Why call dry/wet if dry is better? [In reply to] Can't Post

Er...you still need to have a certain a amount of bioballs for the TT to be effective.

No need to add the bio-liquid to your TT. You can add that in your bio chamber to speed up the production of the good bugs.

Partial water change using anti-chlorine will not kill your good bugs.Smile


SMW1
Veteran

Sep 20, 2002, 9:28 AM

Post #13 of 49 (66379 views)
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Re: [johnson lee] Why call dry/wet if dry is better? [In reply to] Can't Post

I'm a little confused Crazy.

What's so important about the distance between the trickle and the bio balls Unsure ?

I can not understand what difference this makes to the conversion of nitrates.Unimpressed


johnson lee
Veteran

Sep 20, 2002, 9:49 AM

Post #14 of 49 (66377 views)
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Re: [SMW1] Why call dry/wet if dry is better? [In reply to] Can't Post

Hi Stuart

From the little that I know about TT filters, most people using TT filters agree that the distance between the trickle to the bio-balls is important because as the water trickles down, it mixes with O2 along the way which then converts it into nitrous oxide (hence the reduction of the nitrates) and then as it trickles into/onto the bio-balls, the remaining nitrates are also oxidised by the O2 in and around the bio media.

Otherwise, I can't see how the good bugs can thrive in a TT filter when not much of the media gets wet.

I know what you will ask me next: If that is my theory, why the need for bio-balls, might as well just let the trickling water trickle down over a longer distance? I really do not know the actual principle behind the TT but just that it works. Sifu Mark also mentioned that the slow trickle and height do make a difference.

What are your thoughts on this?

Johnson


SMW1
Veteran

Sep 20, 2002, 12:36 PM

Post #15 of 49 (66373 views)
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Re: [johnson lee] Why call dry/wet if dry is better? [In reply to] Can't Post

Johnson



You read my mind Johnston, that is the question I would have asked next. I was only wondering because my TT is 4' hight but only had about 4" between the inlet pipe (which is drilled will about 28 x 8mm holes, and the flocor (had lots of flocor left so I used this instead of bio balls). However since I built the TT within a month the Nitrites went from 0.15 to 0 and the nitrates went from 75 ppm to 15ppm. So I guess it's still working. I will open it up shortly and remove about 8" of bio balls from the top layer and see if it makes much of a difference.

Thanks for the explanation.

Stuart



cwnchong
Koi Kichi

Sep 20, 2002, 1:07 PM

Post #16 of 49 (66371 views)
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Re: [SMW1] Why call dry/wet if dry is better? [In reply to] Can't Post

Struat,

By the way what is flocor?


SMW1
Veteran

Sep 20, 2002, 4:16 PM

Post #17 of 49 (66368 views)
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Re: [cwnchong] Why call dry/wet if dry is better? [In reply to] Can't Post

Flocor is a media which is designed to accomidate the good bacteria. It is hollow to allow good air/water flow and has ridges all around it. It's about a quarter of the price of Japenese matting and about half the price of Bio Balls.


jitwee
User

Sep 20, 2002, 6:16 PM

Post #18 of 49 (66363 views)
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Re: [SMW1] Why call dry/wet if dry is better? [In reply to] Can't Post

Hi SMW1,

The flocor seems like a type of wire protector that used in my company (protecting and decoration purpose). Don't know if it is the same? But it look the same to meCrazyCrazyCrazy.

I have adjusted the height of the water trickle from my pipe to the bio ball (Reduced the amt. of bio ball ). Let's see does it really make a different.......
The immediate impact is 'Noisey' cause water is hiiting at the bio ball at a greater height.


Regards,
jitwee


SMW1
Veteran

Sep 20, 2002, 11:13 PM

Post #19 of 49 (66359 views)
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Re: [jitwee] Why call dry/wet if dry is better? [In reply to] Can't Post

It could well be.

We can use quite a lot of everyday items as media. Look at hair rollers for instance. Laugh


dttk
Veteran

Sep 21, 2002, 8:01 AM

Post #20 of 49 (66349 views)
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Re: [johnson lee] Why call dry/wet if dry is better? [In reply to] Can't Post

Johnson Sly, I'm still doubtful about the nitrates being removed by oxygenation alone and not by oxygen-loving bacteria. If oxygen alone is effective in removing nitrates, then there is no need for biomedia. A thin curtain of nitrate rich water would have been sufficient. Also, I think that if we could get as many bioballs wet from the onset, then there is no need for a certain height between the spraybar and the bioballs Wink. Any comments Sly.
Always friendly :)


SMW1
Veteran

Sep 21, 2002, 10:10 PM

Post #21 of 49 (66337 views)
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Re: [dttk] Why call dry/wet if dry is better? [In reply to] Can't Post

This was my thought exactly.

I know that at least 95% of my bio media gets wet within my TT. I use a 2 inch pipe with many holes that will cover the entire surface (top level with water, the way it is positioned). As I mentioned in a previous post I only have a small amount of space between the media and the pipe.

Maybe the rule of thumb that the media should be a certain distance between the inlet has something to do with the way the water is dispersed on entry to the TT.


johnson lee
Veteran

Sep 23, 2002, 7:19 AM

Post #22 of 49 (66317 views)
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Re: [dttk] Why call dry/wet if dry is better? [In reply to] Can't Post

Good afternoon Dr Tan

Thanks for your input!Smile I am still puzzled by the principles behind the workings of a TT filter actually. It's good that we are having a discussion on this. I have been stumped by some of the questions posed by friends, forum members etc. All I know is that it works!Sly

I'm sure you're right in that it takes more than oxygen to remove the nitrates but I did remember reading somewhere that O2 plays a vital role in assisting the conversion of the nitrates into nitrous oxide.

Seems like I have more questions than answers now!WinkFrown

1. We say that the slower the trickle the more effective the TT filter is. But if the trickle is slow, doesn't it mean that the bio-media doesn't have the chance of getting wet. Water just trickles pass and the media will not get really wet, hence how will the bugs survive? Even as both Dr Tan and Stuart have the trickle well spread out, but due to the slow trickle, I'm not sure if the bacs. survive there well.

2. Eddie Lee posed me this question which stumped me. "If you had a very large pond like say, Dr Tan's, assuming there are lots of nitrates in the pond, how will a small TT filter running at such a slow trickle be able to convert all the nitrates and how long does it take for the water to run through entirely once by the TT's pump? I didn't know how to answer that!Unsure

3. If I remember correctly, Mark Richman did some tests on this and his conclusion was that height and the slower trickle do make a difference to the results.

I too have the same thoughts like Dr Tan and Stuart, but wanted to push this discussion into a different realm by inviting more views on this. Anyone care to contribute their thoughts?Sly

Johnson


SMW1
Veteran

Sep 23, 2002, 9:43 AM

Post #23 of 49 (66314 views)
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Re: [johnson lee] Why call dry/wet if dry is better? [In reply to] Can't Post

This is turning into a very interesting subject once again.

My TT does not really trickle. I guess I would grade it somewhere in the middle of a trickle and a spray. The turnover is quite high, I'm not saying that the water floods out at 1000 gph, but it doesn't trickle out.

With regards to the Nitrates and how exactly they get converted into Nitros Oxide. I do believe that it has to do with the oxygen probably a little more than the bacteria. The reason I say this is ~I have two examples or filters or media that also reduce Nitrates.

Turbo Cleaner - This is supposed to reduce both Nitrires and Nitrates. Although this is claimed by the makers. I personally do not see much difference without the device on, I'm not saying there isn't difference, only that I can not see it.

K1 - This new media is supposed to reduce Nitrates, If used correctly i.e. agressive airation.

What do they doth have in common with the TT ?.

They both use a lot of oxygen. The Turbo Cleaner uses a bubble method and the K1 uses airstones.


johnson lee
Veteran

Sep 23, 2002, 9:55 AM

Post #24 of 49 (66312 views)
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Re: [SMW1] Why call dry/wet if dry is better? [In reply to] Can't Post

Hmmmm....Stuart, interesting food for thought!Cool Must do more research.....Wink


dttk
Veteran

Sep 23, 2002, 3:53 PM

Post #25 of 49 (66307 views)
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Re: [johnson lee] Why call dry/wet if dry is better? [In reply to] Can't Post

Hi Johnson, Stuart, Eddie Smile, Yes,...yummy....this is turning out to be better than I thought! Laugh. Let's answer Eddie's question to Johnson first. I do not depend much on my small TT to reduce nitrates. This is well taken care of by the algae on the walls and my plants! Cool. My single TT is not able to handle all the nitrates that is produced but it is doing it's small bit of reducing nitrate by constantly working 24hrs a day(... like who's isn't...Crazy). Let's just say that it is "helping" my plants to reduce nitrates too. If I did not have plants at all, I would probably need 10 of such TT's to do the job of reducing the nitrate to a decent level as now, abt 40ppm. So Eddie, don't look at my TT too seriously...Laugh. Why did I build it? It was fun and it was an experiment. Can be improved upon as far as the water distribution to the bioballs is concerned...Crazy.

As Stuart mentioned, by slow trickle I don't mean ve...ry sl...ow Laugh. Water should trickle on as many bioballs as possible to keep them wet but not splash on them. In fact there will be more oxygenation of water this way than splashing. Perhaps we should get some confirmation from those people who splashes water on their bioballs to see if that works better. Most importantly, fresh O2 should be able to enter the TT in sufficient amounts. I really do not know if a bacteria exist that removes nitrate Unimpressed. Even if it doesn't, the height of the TT and the trickling of water has shown to be effective in removing nitrates. Sly
Always friendly :)

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