Aquarium Nitrate Filter

Anyone experimented with Nitrate removal using something like this for their aquarium? Since Plants need some nitrates I would think that 24 hour use would be too much but maybe periodic use might be an easy way to keep nitrates very low. I am not suggesting forget water changes but sometimes this might be a helpful alternative in a nitrate control program. I am interested to hear experiances or opinions on this.

http://www.fosterand...-nitrate-filter

Usil

It's a trap! That's just an ion exchanger that will rapidly substitute all the nitrate in your tank for chloride. I don't see that being a great improvement, since the salt will just build up over time without being taken up by plants or algae. It doesn't really look like less work overall than water changes either.

I've had a 55 gallon tank set up since May that had been getting about 20% water changes monthly or even less often. I just bought a nitrate test kit for it today and assumed I'd see off-scale brown (ie several hundred ppm), but it's more like 1 or 2 ppm at most. I just have a couple amazon swords in there, and about three weeks ago I added two water lettuce plants (Pistia Stratiotes). There are now twenty of those, so maybe the nitrate was as high as I feared until recently. Either way, much less messy than that product.

I've had a 55 gallon tank set up since May that had been getting about 20% water changes monthly or even less often. I just bought a nitrate test kit for it today and assumed I'd see off-scale brown (ie several hundred ppm), but it's more like 1 or 2 ppm at most. I just have a couple amazon swords in there, and about three weeks ago I added two water lettuce plants (Pistia Stratiotes). There are now twenty of those, so maybe the nitrate was as high as I feared until recently. Either way, much less messy than that product.

My tanks are the same way. Whenever I used the test kit on this tank, picture: http://gallery.nanfa...uarium.jpg.html the nitrate was always either 0 ppm or less than 10 ppm, and I tested it weekly for months and months without doing a water change. It's fairly common in tanks in which live plants are growing.
My current setup is very densely planted, too, so although I do a 1/4 water change weekly or biweekly, it's not because the nitrate is building up. It's because I've got eight different plant species and I want to avoid any allelopathic chemical warfare between the species. I probably wouldn't bother if I only had a gravity powered siphon, but I own a venturi effect powered faucted connection, so it takes minimal effort on my part and I figure why not.

Usil, I think you should measure your nitrate using a test kit before you bother spending money on a product to remove it. You've got multiple live plants and very bright lights, so if anything nitrate might be a limiting growth factor. There are, off the top of my head, four things that can limit plant growth:
1. Lighting
2. Nitrogen (ammonia preferred, nitrate accepted)
3. Carbon (often in form of dissolved CO2)
4. Other elements like iron, calcium, etc (found in the substrate)

You've got lighting covered. A mineral rich substrate like soil, Fluorite™, or kitty litter usually covers the trace elements. Carbon can indeed be a limiting growth factor, which is why some people inject CO2 using a DIY yeast reactor. And nitrogen can, yes, be limiting to plant growth. This usually happens if you've got CO2 injection going but a light fish load, and ammonia is at 0 ppm and nitrate is also hovering perilously close to 0. As I said earlier that's how my tanks are designed to be; either CO2 or nitrogen is the limiting reactant in plant growth. I like it that way. It's a pain in the butt to do CO2 injection because every week and a half or two weeks or so you've got to dump what is essentially nasty tasting beer down the sink and refill the 2 liter pop bottle with about two cups of sugar and two tablespoons of yeast. And then the plants run out of nitrogen anyway, so you've got to do something like feed your fish way too much or feed them chunks of meat, which rot nicely, and *sighs* it turns out that most plants don't require that sort of effort to grow. I've got rotala wallichii and hemianthus callitrichoides in my tank right now. They're both supposed to be high effort plants. But I've got them just under bright full spectrum lights and with a fertile substrate and not bothering with the nitrogen or carbon supplementation, and they're growing. Slowly, but, you know, it's progress.

What was my point? Oh yes. Don't buy that, Usil. You don't need to lower your nitrate concentration. And if you did want to for some reason, just up your CO2 concentration in the water. A DIY CO2 unit is actually very easy, for all that I whined about it in the previous paragraph. You just keep the 2 liter after drinking soda pop or juice or something, drill a hole in the lid, and attach airline tubing from said lid to a CO2 diffuser ($10 from aquaticmagic, aqmagic.com). It looks like this: http://img203.images...2bubbles4sh.jpg One tip: cut the airline tubing diagonally and pull it through the hole in the soda pop container's cap with pliers, and you won't have to use any sealant to keep it airtight.
If you add a CO2 diffuser, then nitrogen would be the limiting factor in plant growth, and your nitrate concentration would always hover around 0 ppm. (I assume, of course, that you have some sort of nutritious substrate. I've already seen your crazy awesome LED lights in another topic.)

Edited by EricaWieser, 30 October 2011 - 05:27 PM.

I am perplexed then on my nitrate readings for my 55 gallon tank. Many have probably seen my tank in my write-up on the LED light system or checked out my Fish Cam. I have had this up and running since about the end of August. I bought the API Freshwater Master Test Kit to monitor water chemestry and watched the initial tank pass through the the cycle that wound up with 0 Ammonia and 0 Nitrite. However, ever since then, the nitrate levels always seem to be between 40-80ppm. I use this wide range to describe the nitrate level in my tank because with my eyes I see absolutely no difference in the color chart between the red color for 40 or the red color for 80ppm. The color of the water in the test tube fits somewhere in this range but I can't tell where. It is definitely not yellow (0) or light orange (5-20ppm) and definitely not the darker purple/red of 160ppm on the color chart. So, it could be 40 or it could be 80ppm because I simply can't tell. There must be a better way to definitively test for nitrate to get a better quantitative value.

Anyway, I test about every 10 days and since mid September to today (Oct 30) it has always read in this range with the same color. I think I have plenty of plants, my fish do not seem stressed at all and in fact have all probably doubled their weight in that time period. My 4 inch Longear is now a little over 6 inches long and quite robust. The hybrid is closer to 7 inches long and it started out at 5. I have one other long ear and one blue gill both about 5 inches long. Other than these, I have two 1" long sunfish young and an algae eater. I don't think the tank is over crowded and I do water exchanges every 9 or 10 days at about 15-20 gallons each time. There are under gravel filters and an external canister filter that is sized for 125 gallons an hour water filtration (contains physical filters, activated carbon and bio-balls). The water is crystal clear. I am perplexed as to why I am seeing this much nitrate levels but it seems stable at these levels with everything I am doing. I am thinking about removing the current GAC and adding double the volume of new GAC in the filter. Maybe the new activated carbon might drop the nitrate level.

I am open to suggestions or is what I am seeing normal?

Usil

Edited by Usil, 30 October 2011 - 09:35 PM.

There are under gravel filters and an external canister filter that is sized for 125 gallons an hour water filtration (contains physical filters, activated carbon and bio-balls). The water is crystal clear. I am perplexed as to why I am seeing this much nitrate levels but it seems stable at these levels with everything I am doing. I am thinking about removing the current GAC and adding double the volume of new GAC in the filter. Maybe the new activated carbon might drop the nitrate level.

Filters are homes for nitrosomonas and nitrospira bacteria. Because your ammonia and nitrite are at 0 ppm, you know that there are enough nitrosomonas bacteria to convert the ammonia to nitrite and enough nitrospira bacteria to convert the nitrite to nitrate. Adding more filter media or another filter would not affect your nitrate level because the bacteria are already doing a perfect job converting the ammonia to nitrite and then to nitrate.

You shouldn't rely on activated carbon to remove nitrate. Activated carbon has very little effect on nitrate itself, and it is more often used to remove tannins and chlorine. Also, it's impossible to tell when activated carbon is 'full' and starting to release nitrate back into your water.

There are two ways that nitrate can exit your water column. It can either go down your drain via a water change, or it can get incorporated into a plant as new tissue (for example when the plant grows a new leaf). That means that there are two ways for you to decrease the nitrate concentration in the tank. You can either increase the volume of water removed from the tank during a water change, or you can increase the rate of growth of new plant tissue.
Let me give you an example. If you were to remove one quarter of the water in your tank, you would dilute the nitrate concentration from 80 to 60 ppm. If you were to remove one half of the water in your tank, you would dilute the nitrate concentration from 80 to 40 ppm. If you were to remove one half of the water in your tank, top it off, and then remove one half of the water again, (a 3/4 dilution), the nitrate concentration would be 20 ppm.
Adding live plants to the tank is also an easy method to decrease your nitrate concentration. It is common in aquariums with fast growing plants to run out of nitrate, the plants use so much of it to grow their new tissues.

There is a certain amount of debate as to what concentration of nitrate approaches being toxic for the fish. The reason for that debate might be because the nitrate sensitivity really does depend on the species of fish you're talking about. If your fish are doing fine, then they're doing fine. But the long term toxicity of a compound is often a lot lower than the acute toxicity, so just because you don't see any immediate signs of damage doesn't mean that they're not suffering in some way over the long term. I know that I cannot personally judge what a safe level of nitrate is for the fish in my aquarium because I am using only my short term observations, not any long term studies, to determine whether or not the fish are suffering. My own opinion is therefore that I would rather be safe, and keep the nitrate levels as low as possible, than sorry. Most tropical fish enthusiasts believe that a concentration above 30-40 ppm approaches danger levels. My own aquarium has a nitrate concentration around 10 ppm because of the large volume of plants living and growing in the tank. But I haven't measured it recently, so maybe it's higher. *goes and measures* *comes back* I just used Jungle Labs' "6 Tests in One Quick Dip". The nitrate was around 0 ppm, definitely nowhere near 20 ppm (the first color box labelled on the test). *nods* Yup. Plants are awesome.

Edited by EricaWieser, 30 October 2011 - 11:12 PM.

Thanks for this. Is there any better quantitative way to get accurate Nitrate levels? Or, I guess I just need it to get down sufficiently in the yellow (<10ppm).

As for plants, I am going to wait a few weeks to see if current plant growth is effected by the extra light I have and see if that effects nitrate levels. If not I guess I will go on a campaign to increase water exchanges for a few weeks. I have read about using CO2 but have not decided to go there yet. As I like to tinker I might consider trying this but not till I see the effect of the extra light on the current plant growth. No sence in adding variables at this time as I wold like to be clear on cause-effect relations in my aquarium.



Usil

Edited by Usil, 30 October 2011 - 11:22 PM.

I am perplexed then on my nitrate readings for my 55 gallon tank. Many have probably seen my tank in my write-up on the LED light system or checked out my Fish Cam. I have had this up and running since about the end of August. I bought the API Freshwater Master Test Kit to monitor water chemestry and watched the initial tank pass through the the cycle that wound up with 0 Ammonia and 0 Nitrite. However, ever since then, the nitrate levels always seem to be between 40-80ppm. I use this wide range to describe the nitrate level in my tank because with my eyes I see absolutely no difference in the color chart between the red color for 40 or the red color for 80ppm. The color of the water in the test tube fits somewhere in this range but I can't tell where. It is definitely not yellow (0) or light orange (5-20ppm) and definitely not the darker purple/red of 160ppm on the color chart. So, it could be 40 or it could be 80ppm because I simply can't tell. There must be a better way to definitively test for nitrate to get a better quantitative value.

Anyway, I test about every 10 days and since mid September to today (Oct 30) it has always read in this range with the same color. I think I have plenty of plants, my fish do not seem stressed at all and in fact have all probably doubled their weight in that time period. My 4 inch Longear is now a little over 6 inches long and quite robust. The hybrid is closer to 7 inches long and it started out at 5. I have one other long ear and one blue gill both about 5 inches long. Other than these, I have two 1" long sunfish young and an algae eater. I don't think the tank is over crowded and I do water exchanges every 9 or 10 days at about 15-20 gallons each time. There are under gravel filters and an external canister filter that is sized for 125 gallons an hour water filtration (contains physical filters, activated carbon and bio-balls). The water is crystal clear. I am perplexed as to why I am seeing this much nitrate levels but it seems stable at these levels with everything I am doing. I am thinking about removing the current GAC and adding double the volume of new GAC in the filter. Maybe the new activated carbon might drop the nitrate level.

I am open to suggestions or is what I am seeing normal?

Usil

Usil,
Sounds like your fish are growing and happy. Your nitrates are well within tolerable limits for the species and are stable. As Erica said, plant uptake of nitrogen can be limited by other factors. And, as gzeiger said, the product you are looking at is an ion exchange system; very, very, very much like a water softener system. If it were me, since ammonia and nitrites are cycling fine, I would continue to do what I have been doing and continue to monitor the system (and forget being perplexed).

After all, only two months have passed since the system was set up. I have kept fish in isolation tanks longer than that before introducing them to a long established tank (for prophylactic treatment and disease prevention of my established fishes)! And I have kept fish in breeding condition in tanks without live plants and fewer water changes than you utilize, and less filtration than you have, for several years. With all the various factors that could be involved, it would be hard pressed for anyone (methinks) to accurately explain the reason why your nitrates are hovering in the 40-80 range without an unlimited budget and testing.

As for the "better way" to test for nitrates, there are some more accurate testing kits out there such as the HACH kits. However, for your purposes, I don't think the several hundred dollars investment would be necessary or cost effective. (If you were considering an intensive aquaculture system in which thousands of dollars of fish were at stake, it would be a much different story).

I suspect that new or additional activated carbon filters will have little effect on the nitrate levels. They are excellent for removing Roundup, chlorine, etc., but, (in my experience), have limited effect on normal tank nitrogen compounds. Yet they are cheap and it doesn't hurt to keep using them!

For the record, I have had the opportunity to check the results of the API master test kit against the HACH and found the results very similar.

I had considered that I might still have what would be considered a 'young' tank and need to wait a bit to see what happens. I am not going to spend hundreds on testing so will wait a bit and see if extra plant growth will effect the current equilibrium.

Usil

Erica, I can tell by looking at that picture that your tank would have zero nitrate. But when I say I had "some sword plants," I mean there were two scraggly little things barely hanging on under a wad of algae the size of my fist, and nearly an inch of mulm accumulated across most of the bottom, ranging from fish poop to whole plant leaves. When I would clean the glass, there would be a film of algae visible from 10 feet away regrown that same afternoon, so I figured there had to be a nutrient problem. I assume the water lettuce cleaned it up more or less right before the test.

Usil,
I agree with what others have said here - I would not use the nitrate filter you described, since you want that nitrate for your plants.

Are you adding any chemicals when you do your water changes? Apparently some of them can affect the result of test kits. I know the API ammonia test kit is affected by conditioners that remove chloramine or otherwise "neutralize" ammonia. Not sure about nitrate.

Regarding other things - you need to ask yourself what you are looking for out of your plants. Some people like them to grow as fast as possible. Some people (myself included) just want good growth and a nice, lush tank, without so much growth that maintenance is no longer fun. Getting the best lighting will help with both goals. CO2 would (in my opinion) interfere with the second. Some people love to tinker that way, but some would rather not have the added maintenance. I've had a lot of very, very nice looking plant tanks without CO2 and dosing of fertilizers, as have many others on this forum and elsewhere. I'm not saying you shouldn't do it, just saying you don't have to.

If your fish load is "heavy" relative to plants, then floating plants with dry-surface leaves (pistia, limnobium, duckweed, etc) will provide the best nitrate removal because they can get all the CO2 they need directly from the air (assuming something else isnt limiting like PO4, Fe, Ca, etc)