Reducing Nitrates

ercnan

ercnan

Bar's Open
Sep 8, 2005
46
0
0
Indiana
Hello All
First post and first time trying plants.
Questions abound right now, but I'm learning loads from you all.
A little info. on my setup fist I guess.
125G freshwater with south american cichlids.
2 small oscars
2 large severums
1 medium pleco
1 large pike

PH 7.0
KH/GH 4.0 degress
Ammonia 0 ppm
Nitrites 0 ppm
Nitrates 40 ppm

The filter currently consists of 2 Emp. 400 HOB's along with a wet/dry running around 900gph.

Lighting is currently 1 4ft triple tube "shop" light centered with 1 40w gro-lux, 1 32w standard "cool" white, and 1 40w power-glo. In addition, also on either side of this unit are single ceramic screw in fixtures with each one holding a 125w spot-gro. Everything is suspended approx. 12" above the glass.

The inital problem was very high nitrates (80-160 + ppm)
50%-90% water changes reduced it to tolerable levels, but only for a short (couple days max.) time.

I've added in the last week or so, anacharis floating, pennywort floating, water lettuce floating, and some houseplants with just the roots in the tank (philodendron and peace lilly) in an effort to combat these nitrates.
So sar it seems to be doing the job fairly well. as the nitrates are giong down.

I guess i'm curious about a few things right off.
1.) Do I have enough light.
2.) Do I need ferts. or just let the plants use the nitrates until they drop to 5-10ppm.
3.) Should I be thinking about CO2 injection. (A chart I found relating KH and PH shows 12.5ppm CO2 , with an ideal range between 10-20ppm.

And probably pages more, but these will do as a start. I'll keep reading as well.

All opinions and thoughts welcome.

Thanks in advance for your help.
E
 
1) Your lighting is for floating and emersed plants, not submerse, so the common rules of thumb do not apply. At that height about the tank, you should have enough light for those plants, but the Spathiphyllum (Peace Lily) gets much too large to fit within that height.

2) Judge that by the plant's growth. Assuming that you continue some reasonable water change schedule, the plants will tell you if they need things that are not in the fish waste or your water supply.

3) No, you should not need CO2. The charts for KH/pH/CO2 assume no organic acids and no other buffer system. In a heavily stocked tank, you will have significant organic acids. Air equilibrium for CO2 is 4-5ppm max at sea level, with heavy stocking you may get a bit more, but 12+ppm is unlikely with any surface breaks at all. With 2 HOBs and a W/D, you have very significant surface breaks. Bet on organic acids in the water.
 
RTR
Thanks for the reply.
I do regular water changes/gravel vacs. every week. Usually around 50%
More so lately because of the high nitrates.
About the wet/dry.
I'm hoping to remove this at some point as I've read the are really good at nitrification, but are labeled as nitrate factories. Not to mention the noise factor.
My goal is to hope to have enough plants to take care of the fish, and let the Emp. 400's do mech. and circulation chores.
Does this seem reasonable/logical/feasible given my current fish load ?
Soon to be minus 1 large pike, as he is waiting for his 75G to be ready.
Thanks again
E
 
I like W/Ds a lot. I do get annoyed at all the folks who rattle on about W/Ds being nitrate factories. They are biofilters, right? The job of a biofilter is to convert toxic fish waste in the form of ammonia to equally toxic nitrite and then to much less toxic nitrate. They do their job. ALL biofilters are nitrate factories, that is what they are designed to do. If ammonia is not oxidized to nitrate, it kills fish. I really do not understand how folks expect biofilters to function otherwise. I suspect it is lack of understanding on their part of basic captive environment biology. If you have stock at a certain bioload, you must have a process for detoxifying their ammonia production. Biofiltration is the most widely used process for that control, and W/Ds are among the highly effective formats for that.

Yes, there are alternatives. Heavily planted FW tanks or external veggie filters of sufficient size and plant mass and growth rate can negate the requirement for a biofilter, certainly. But there are many fish incompatible with heavily planted tanks, and external veggie filters may require anything up to doubling the original tank's volume plus additional lights and frequently additional pumps and supplements. There are trade-offs involved. In SW, live rock and plenums or DSB can serve the same function, as can 24/7 lighted refugia with macroalgae. There are still tradesoffs there.

Noise from W/Ds is a design factor. There are relatively quiet designs around which are certainly much quieter than the majority of commercial products. None however are as quiet as an Eheim canister, but certainly less noisy than most HOBs. Even the CO2 blow-off is largely controllable.

Whether your existing plant use will control excessive nitrate buildup is too individual to predict. Total bioload, feeding practices, water change schedules and size, and speed of growth of the plants are all factors. This is something everybody has to explore on their own. I have had one setup where the addition of multiple veggie filters (two on the same light cycle, one on reversed light cycle) with total filter volume exceeding the display tank was still insufficient to control nitrate without alternate day water partials. But the fish and it's bioload were huge.
 
RTR
Thanks again.
A lot of helpul info. to digest.
I understand the biofilter process, that all are technically "factories", and the reasons why some are better "more efficient" than others.
I also understand the different varibles that are associated with that process.
My initial reasoning for the plants was not to try to get completely away from the maint. of doing water changes to drop nitrate levels, but to try to add in another natural process that by nature's design, does essentially the same thing.
I understand that we as fish keepers can never match nature's complete balance, but I think the more natural processes that can be implemented, the better.
I don't mind doing water changes or whatever else needs to be done to do my best to insure the health of my fish, but I also think that if I can do something that helps the tank better support itself in a more natural way, I'm only making things better.
I mean, if I have to change 50% of the water everyday, or remove some fish, to keep down the nitrates, so be it. But on the other hand, if I can add enough plants to only have to do that water change every third day, to me that's better for the tank's health, as well as less stress on the fish.
High nitrate levels don't directly affect me, but they will over time directly affect the fish. I'd hate to have to deal with HITH simply because high nitrate levels don't directly affect me.
If that doesn't affect me , then I should choose something else for a hobby.
I'm sure it would be great to have a completely natural ecosystem that required only someone to stare in awe at it, but time, space, and money constraints make that a virtual impossibility.
I enjoy sitting and watching fish. What makes it even more enjoyable, is knowing that I am doing everything I can (within the confines of 125g of water) to make those fish feel
as if they were in their natural habitat.
Thanks again for your input. Your thoughts and opinions, as well as others who may join in, are quite valuable, and the reason for my post. I know some aspects of this hobby are cut and dry fact, but quite a bit is open for discussion. What works for one, may not for another.
We all strive to meet that "perfect" balance, which is why we post to begin with.
Talk to you soon.
Take Care.
E
 
Wet-drys are nitrate producers. They are because they are so efficient. I have used them before and I still have 2. For a heavily planted tank or if you have a heavily populated tank they are better to use (plants need nitrates and nitrates are not as toxic to fish.

As long as one understands this it is fine. You just can not say --"Oh nitrates are safe" and have your nitrates at 100ppm!!
 
Nitrates are used in FO tanks as a rough measure of general pollution (most of which we cannot measure). In heavily planted tanks, we cannot use that measure as plants use ammonia and nitrate for the nitrogen it contains. If the bioload is not too large, there will never be any nitrite because the plants will use the ammonia before the bacteria establish or get the chance to oxidize it to nitrite. If there is ever ammonia or nitrite, then you do need a bacterial biofilter.

Nitrate toxicity itself is not well defined (and is highly species-specific), but in FO tanks it is an excellent indicator of pollution build-up. In heavily planted tanks, you may lose that indicator.

In the setup for my mbu, I still had biofilters (both Eheim bio-only canister and a W/D) with the veggie filters. But, as you say, it was definitely a healthier system than conventional filtration only. And the nitrate build-up was much slower than it would have been otherwise.
 
tanker
Yes, I have found out that the w/d concept is very efficient at bio-filtering. Not much IMO for mech. though. Unless of course everything floats.
I guess I'm just hung up on nitrates because yes, 10-20ppm may be tolerable in my case, but I was having serious issues (80-100+ppm) 2 or 3 days after a major (70-80%) waterchange. I'm not exactly sure why they were going up so fast, as I don't really think my fish load is too much, but it seems the few plants that I've added are helping bring them down to a more managable level. I know plants need nitrates and other things as well, and that's why I put them in there.
Just trying to manage a problem in a different way than just changing water everyday.
If I have to, that's cool, but if I can find a different way that works, that's what I'm after.
Thanks for the reply.
Take Care.
E
 
RTR
Thanks. Exactly my point. Even if I could balance only the nitrates. (used up at the same rate of production) I would still need to do waterchanges to add back everything else, or take out everthing else, depending on your view.
I'm really just trying to slow down the rate at which the levels increase, not completely stop it.
Having just switched from africans to south americans, and given the stories I've read about how S/A's are more prone to HITH and other issue based on water quality, maybe I'm being a little paranoid about this nitrate issue.
With the africans, I either never had this problem, or it was masked by the difference in water type.
It's just strange how I could have 20-25 africans in the tank with 15-20ppm nitrates, take those fish out, drain 90% of that water out, refill it with softer, lower PH water, put 6 fish in it and BOOM! 3 days later the nitrates are off the charts. Change 80% of that water and, after 3 days, off the chart again.
Take Care.
E
 
What substrate depth did you use, and even more important, was it fully accessible to vacuuming? After my first mbuna tank showed high nitrates routinely (unlike yours) and nitrate rebound after partials as in you SA tank, I tore the tank down and went of over-engineered RFUG. The massive rockwork made it impossible to vacuum and I had excessive substrate anyway. After the change-over coupled with some other filtration changes, I had no more nitrate rebound post-partial. Substrate can be a wonderful reservoir of nitrate. That taught me to never use more than I had to have (other than in heavily planted tanks), and always to have a technique for keeping it clean.
 
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