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Re: Reducing nitrates

> Subject: Reducing Nitrate - Newbie - Freshwater Plenum?
> I've been keeping fish for a few months now, so I've still got a lot to
> learn!  I've certainly made some mistakes, which is why I am posting this
> (I've also sent to a fishkeeping magazine here in UK and some newsgroups - I'd
> like to get several opinions).
> The problem that I'm having is with high nitrates.  I have three tanks and one
> to set up, the tanks are:
> lengthxheightxwidth
> 48x15x12 - Eheim 2227 Wet/Dry filter and Fluval 4 (internal). 1x42 inch
> fluorescent tube in a 'marina' hood.  30 inches of fish.
> 30x18x12 - Interpret Prime 10 and Fluval 3 (internal). 1x24 inch fluorescent
> tube + reflector  20 inches of fish
> 19.5inch diameter x 20 inch tall hexagon - Fluval 204 and ClearSeal internal
> filter (similar to a Fluval 1 or 2).  1 x 12 inch fluorescent tube + reflector
> and a 'pygmy' lighting unit with a domestic 'energy-saver' fluorescent bulb.
> 8 inches of fish
> 48x24x8 - 2xTrio2000 and a Rena iv1 (this tank is not set up yet). 4 x 18 inch
> fluorescent tubes (2 blue moon, 2 tritons).
> All lights are on 14 hours a day (I did have them on 12 hours, but increased
> the time to try and help the plants.  It has had no effect though).

10-12 hrs is good for plants.
> When I started out I saw a product Tetra EasyBalance which Tetra claims to
> make it unnecessary to do water changes for 6 months if used (it also suggests
> that Nitrates are controlled).  It hasn't worked for me though (I am still
> adding it to replace vitamins and so on with water changes though)

So don't use it.
> Each of the tanks is planted, though the plants do not fare too well, and hair
> algae has the upper hand.  I am currently fertilising the plants with
> proAquaPlant from GreenLine aquatics in UK (it's a 'tea-bag' type packet that
> you place in the water and which is meant to last about 3 months).

Seen it once. Do you have CO2? You have plenty of other equipment. You do
not have enough light. For the 48inch tank you'll need about 80 watts or so.
The other tank(30 inches) about 60 watts, the hex will need about 30-40
watts or so and the new tank should have about 100-120 watts. These are mid
low ranges for lighting.
> Over the last three months I've lost a fair few fish to illness.  It looks
> mainly like internal bacterial infections (particularly gillrot).
> I did treat this with Interpret remedies and Melafix (followed by water
> changes at the end of the course of treatment), however the affected fish
> often died anyway (it was only ever one or two that were ill).  In hindsight,
> I'm assuming that the illnesses were able to attack the fish due to what must
> have been excessively high nitrate levels.  At the time I wasn't testing
> Nitrate,and water changes were infrequent (only after medication) because I
> assumed that the EasyBalance would work.

What is your tap water's level of NO3 and PO4 (Nitrate and phosphate)?
Call the water company up and ask. Many in Europe and some parts of NA have
high NO3 and PO4's. You could be adding 40ppm of NO3 from the tap water each
time you do a water change.
There are ways around this issue though.
> At the moment I'm doing weekly water changes (50%) and using rechargable
> nitrate removal pouches to keep the Nitrate levels down (although there is
> still a problem with hair algae, and the level is still higher than I'd like
> by the end of the week).  The fish are much healthier and happier under this
> regime, but the plants remain fairly unimpressed!

Likely due to the above tap water condition then.

> 0.  However my Nitrate readings will raise from ~5 to ~100 mg/l in about a
> week (even with the 50% water changes).

Hummm. Well what goes in is causing that reading(or lese the kit is bad).
Hobgoblins do not come in at night and add NO3:-)
> I want to keep the Nitrate levels down more effectively (and if possible
> reduce the required frequency of water changes).  And I do have an idea which
> I'd appreciate your comments on.
Grow the plants well, they remove gobs of NO3's.
> I'm thinking of setting up a plenum filtration system (like the Jaubert Plenum
> for Marine fish), with some modifications.

Questionable for salt, useless for planted tanks.
> The plenum itself would be constructed from eggcrate and either covered on top
> with gravel tidy, or something impermeable (in which case the
> sides/overhang would be covered with gravel tidy to allow water into the
> void-space).  The reasoning for suggesting an impermeable top cover is that I
> understand plant roots will actually oxygenate the substrate, I don't know how
> much they would oxygenate it or whether they would
> disturb the anoxic conditions required for denitrification.

Try a coil denitratifer. Also if your tank after a water change has 5ppm of
NO3, something in the tank is producing the NO3(fish food, rotting plants,
all those med's you've been adding etc).

> There would be a length of airline tubing running into the plenum so that I
> could extract water from the plenum if required (in case of hydrogen sulphide
> production).

Don't do this. 
> I was planning on having an undergravel heating cable either above or below
> the plenum (I'm unsure which is better, because I assume there must be some
> water movement in the plenum so that low-oxygen water can enter and so that
> waste does not build up).

Again, don't do this.

> The final addition would be CO2 injection into the aquarium (not into the
> plenum), to assist the plants.  For this I would plan on stopping
> the CO2 overnight, and possibly switching on the airpump during the hours of
> darkness (since both plants and fish consume oxygen in the dark
> - - or so I've been told).

Do this, but you don't need the airstone on at night, O2 levels in a well
growing plant tank are very high(higher than the air for the most part of
the 24 cycle). You will actually blow off O2 for the first part of the
night(adding air at the last 4-6 hours before the lights come might be okay)
> I'm hoping that the combined approach (encouraging plants, and using a plenum)
> will assist in keeping the nitrates lower.  This in turn should result in
> happier fish, and a better overall look for the aquaria.

You encourage the plants _alone_ in a moderately stocked tank you will need
to add NO3's if you tap water is 5ppm or less.
> I don't have a low-level understanding of the
> science behind it all, so I could just be creating a lot of work and spending
> money, for little benefit to the fish and plants.  Your comments would be
> greatly appreciated, both on the plenum idea, and the current set-up (I've got
> substantial conventional filtration on each tank, but from
> what I've read recently, it seems as though this may be making the problem
> worse rather than better  - can you overfilter?).

Not in your case right now.

Since you have the funds, get a CO2 system. See about adding multiple needle
valves on your CO2 gas tank and regulator. By getting a separate needle
valve for each tank(these are relatively cheap 20-30$ US) and adding a "T"
you can chain out as many CO2 lines to each tank that you want to add CO2
to. That way you will not buy a separate system for each tank and this will
save you many $ or lb's in your case. Forget about the plenums. Get some
good gravel in the 2-3mm range add some laterite etc. Add more light.
I'd suggest you learn as much as you can about CO2. Check the
www.thekrib.com for more info. Learn as much as you can about CO2.
Tom Barr

> Dominic Large