What Is A Safe Maximum Nitrate Level For Freshwater Fish?

I'm under the same impression that filter cartridge performance falls off a cliff rather than showing a gradual decline.
I'll see what information I can find about roughly how long the filters last/how much water they will filter, and make sure that I have a spare ready in plenty of time. Saying that, I ordered the current ones directly from Pozzani and they were delivered the next day, so that was great.

I'm afraid so, and the filters will be working hard with the water I have here.
From some of the information I've found today it looks as if the nitrite removal filter will do somewhere around 600-800L water, taking it from 50ppm to 0.  With my levels of 40ppm, and with my number of tanks, it won't take long to wear out a filter. Looks as if I'll be getting a replacement in sooner rather than later. 
Still, I won't have to buy RO from MA, and the fish should be better off with this filtered water. 

That's a difficult one because I don't use RO in all of my tanks, but do plan to use filtered water in all of my tanks.

I buy RO from LFS @ £3.50 per container (20-25L), and use approximately 3 containers a week, mainly on the river tank, and to top up any evaporated water in other tanks. Assuming a 4 week month, I spend around £42 a month on RO to drop the GH down to 14, with no significant impact on the nitrate levels on the river tank.

The nitrate removal filter cartridge and water hardness removal cartridge were £35 each, plus delivery of £5.95. Information I've found indicates the filter will do 600-800L tap water. One chap said his did 600L, starting with nitrate levels of 50ppm, and taking them down to 0. I will be using low nitrate water in all tanks, and expect to use at least 1 filter a month. Individual replacement cartridges are £13.95.

I will not be using the hardness reduction filter cartridge as much, and estimate that I will be using it less than half as much as the nitrate cartridge. Costs are £35 a cartridge (no replacement filters).

So, assuming I wanted to use 1400L/month water with 0 nitrate, and 700L with 0GH, I would use 2 nitrate filters and 1 hardness reduction filter = £90 for first month, then £55 each month after that (including delivery costs for cartridges).

Assuming I wanted 1400L/month RO = £196 a month (not including cost of purchasing containers).

Obviously RO is pure, and the water I get through the filters is not. Also, I've not included the cost of attaching the filters to the water system, which for me was around £25 for a water change kit similar to the Python ones.#

However, if I was just planning on using the water in the river tanks, the calculations would look like this:-
RO water 300L/month = £42 a month = £504 per year.
Filtered water 300L/month = 3,600L/year = £200 per year
Assuming 1 nitrate filter cartridge and 4 replacement filters = £95
Assuming 3 hardness reduction filter cartridges = £105

Sorry the answer has been quite long and rambling. Basically, due to cost I wouldn't have considered using RO in all of my tanks. I also struggle transporting the large containers from the LFS, especially lifting them out of the boot of the car and getting them into the house. Using the recently purchased water change kit made me realise that I could use that for the filters, rather than attach the cartridges to the pipes under the sink, which made looking at reducing the nitrates in my tanks a more reasonable idea. I won't be getting the nitrates to 0 because the filters also impact the KH & pH, but anything less than the 40ppm in my tap water will be better for the fish.

Yes, this is indeed extremely interesting, so thanks for the clear and methodical write-up. 

Just discovered this topic as I'm new to the forum.  I live in the Oregon, US, but was surprised to learn that people in the UK are living with 50 ppm nitrates out of the tap.  I have zero.  BUT....I have higher ph that I would like for most of my fish.  I got a reverse osmosis system years ago, for my own drinking water, and what I do now is half and half RO and tap water to achieve the right balance.  So might it be worth it for people that have high nitrate PPM out of the tap to invest in an RO system and mix with the tap water? 

I haven't read through the whole thread so if this has already been discussed, forgive me.

A few years ago I read a paper - haven’t been able to find it again since - that studied the effects of nitrate - acute and chronic - on various fish, freshwater and marine, and a few other watery lifeforms. The fish species studied weren’t representative and there were only a handful that are aquarium fish, but the study did conclude that some species are harmed by as little as 10ppm (some were far more tolerant, into the hundreds).

Hi,

Just looking back over nitrate-related stuff and spotted your post.

So, when discussing nitrate toxicity, what I glean from this is that it is important to distinguish between acute and chronic toxicity.

JPC

That is the most commonly used test kit in the UK as well.


Do you live in an agricultural area? That is the main reason for nitrate in tap water. I am lucky that my water comes from a reservoir with very little agriculture around it so my nitrate is very low.




I know that some Americans are horrified that the UK allows 50 ppm nitrate in drinking water and they say that the maximum allowed in the US is 10 ppm. The different way of measuring it means the two are almost the same.

Do you live in an agricultural area? That is the main reason for nitrate in tap water. I am lucky that my water comes from a reservoir with very little agriculture around it so my nitrate is very low.

I live in Linn County 65 miles due south of Portland.  Linn County calls itself "the seed capital of the world".  Lot's of grass and hay.  And some farms producing cattle, sheep, dairy and fruit.

the API Master test kit -  aaah.. his response - it  is completely 'unreliable' at the higher readings - sorta 30 or 40ppm and upwards..  they no longer use it in their business. He recommended the Tetra Nitrate only  kit ( about £9 ) which I bought. On testing my tanks, now between 2 days and a week since last water changes, they all read close to half of the API test readings, viz: 90L community tank 60 ppm down to 35ppm,   250L community (bigger fish) 25ppm down to 15ppm, the 350L 20-ish cichi tank 40ppm down to 25ppm.. conclusion, I'm gonna keep chkn nitrates in the tanks using the Tetra kit. I was also told that API kit will rarely give a clean zero for ammonia, again my experience - it's always sorta 0.1..but I'll take that.. and lookin' to get individual 'single-chemo' kits in the future. My  reduction in water bill will easily pay for the new kits, lol.. 

Ok, separate from Sue's statement about different standards between UK and US, SEACHEM claims that the API test kit test for TOTAL ammonia.  They say if you use their product PRIME, that it binds a portion of the ammonia rendering it non-toxic (for about 48 hours).  So, after using PRIME, the API test kit will still show an elevated ammonia level, but most of it has been bound by PRIME and is not "free".  I take it that this may be self-serving, because SEACHEM's next recommendation is to buy THEIR test kit, which only measures "free" (toxic) ammonia and is therefore more accurate.  Or by using their little "Ammonia Alert" badges, which hang inside the glass of the tank.  I am a little cynical about the claims of all these vendors, and I would take with some caution your local fish salesman that happens to have become convinced the Tetra product is better.  In the US, Tetra sells "test strips" and they many people have found them to be inaccurate and not consistent with other measures.  If I had to put my money on any of these companies with regard to their product reliability, I would be more likely to trust SEACHEM than TETRA.  Just my humble opinion

I didn't make myself very clear, sorry.

The home nitrate testers are the same the world over. They test nitrate-NO3.

The thing which differs is water testing companies nitrate results. I wasn't sure if you were saying that 50 ppm allowed in drinking water in the UK was the reason that so many regions of the UK have 40+ ppm - that water companies don't have to try hard to get it lower. But that in the US, the legal limit is something like 10 ppm so US water companies have to make sure they get it down below that.
I just wanted to say that the US upper limit is virtually the same as the UK upper limit; they just appear different because of the way they measure it. So the reason that a lot UK nitrate levels are high is for some other reason.



As for ammonia, our liquid reagent test kits read total ammonia - ammonia and ammonium combined. And when a dechlorinator of any brand which 'detoxifies' ammonia is used, the 'detoxified' ammonia also registers in the test.
Most, if not all, of the liquid reagent home testers use the salicylate reaction. The FAQs on Seacem's website for Prime state

A salicylate based kit can be used, but with caution. Under the conditions of a salicylate kit the ammonia-Prime® complex will be broken down eventually giving a false reading of ammonia (same as with other products like Prime®), so the key with a salicylate kit is to take the reading right away.