Nitrate test

[Airborne 82nd]

I thought I posted this but I don't see it so here goes again. Moderators feel free to remove if this is a do over.
How soon after a pwc can you retest for nitrates? I did a 50% change (35gals) 75 gal. tank but I figure 70gals. of water. I used 2 cap fulls of prime= 100gals. I'm running a fluval 407 and a tidal 75 so there is a lot of water turnover if that matters. Before pwc nitrates were 15ppm they got away from me while out of town. I'm not sure about the math but would a 50% pwc bring trates down to7.5ppm?

 

[Andy Sager]

Yes, the math works but you use it as an approximate because unless you know exactly how much water is actually in the tank, the results may be different. How soon after a water change to test will depend on how much water your filter is turning over. You want the water to turnover at least 3 or 4 times before testing so that it's unlikely to get water that hasn't been diluted or hasn't been circulated into the tank water.

 

[Aiken Drum]

If your nitrate is 15ppm and your new water is nitrate free, then a 50% water change should result in 7.5ppm. Once the new water has had chance to thoroughly mix it should test at the lower figure.

A lot of tapwater has nitrate in it. I think in the US, EPA standards for potable water is upto 10ppm, but many people there have higher levels than that. Here in Europe and the UK the limit is 50ppm. I have about 5 to 10ppm in mine, but I know people in London are as high as 50ppm. So a 50% water change won't result in a halving of the level.

Remember though that it's a home test kit, not laboratory testing. Its not all that accurate a test. And can anyone really tell the difference between say 10ppm and 20ppm? So you could have say 30ppm nitrate, which looks like say 20ppm test result. After your water change.it would be 15ppm, but still look like a 20ppm test result. It's really not worth getting too hung up on numbers.

Some of the tests aren't even for what they say they are on the bottle. The ammonia test is actually a test for total ammonia nitrogen. The KH test you posted about yesterday is actually a test for alkalinity. The nitrate test will show a positive result for nitrate in the presence of nitrite. Nitrate testing is an issue even for laboratorys, for instance done by your water company, due to other contaminants throwing off tests.

 

[Airborne 82nd]

Thanks Aiken & Andy
So I guess the best I can hope for is to at least see some change in the color. I will test my tap water and maybe some distilled water to see how they compare in color. You are correst in telling the difference between say 10ppm and 20ppm. To my eye it looked like it was between those two numbers (colors) so I called it 15ppm. The only reason I take this test is to get an idea of how dirty my water is. ie do I need to do a 50% change or more. I've noticed that the bigger the fish get the more I need to change water. I think I will rename them to Sir poops alot One last thought when testing my tap should I use prime in it first?

 

[Andy Sager]

Thanks Aiken & Andy
So I guess the best I can hope for is to at least see some change in the color. I will test my tap water and maybe some distilled water to see how they compare in color. You are correst in telling the difference between say 10ppm and 20ppm. To my eye it looked like it was between those two numbers (colors) so I called it 15ppm. The only reason I take this test is to get an idea of how dirty my water is. ie do I need to do a 50% change or more. I've noticed that the bigger the fish get the more I need to change water. I think I will rename them to Sir poops alot One last thought when testing my tap should I use prime in it first?

I'll tell you from experience, when your Oscar gets close to full size, you should be changing some water at least 2-3 times per week. Sir Poops a lot is an accurate name for them. LOL But he's the kicker: Big fish sh*t big poops which means more nitrates faster. That IS the biggest problem with large fish. I loved my Oscars but they were a real time consuming fish. The only way to avoid this is to run a pipe into a large field of plants so that they absorb the nitrates before returning to the main tank. It's similar to a refugium in saltwater tanks.
As for the Prime question, PRIME does not remove nitrates but does neutralize them so I would test your tap water with and without the PRIME to see if it makes a difference.

 

[Airborne 82nd]

Thanks I just was not sure if clorine would throw off the nitrate test. So I will test it both ways to see. I have the time so the next step is a larger tank with that I have some plans to make it easier to work on the changes are not worth it for this 75gal.

 

[Andy Sager]

Thanks I just was not sure if clorine would throw off the nitrate test. So I will test it both ways to see. I have the time so the next step is a larger tank with that I have some plans to make it easier to work on the changes are not worth it for this 75gal.

Think swimming pool and a float valve on a line that has something like a Culligan brand filter so you don't need to worry about chloramine.

 

[Airborne 82nd]

Just a follow up on my new nitrate test. Tap water with and without clorine 0ppm or bright yellow Tank water 24hrs after pwc 0-5ish ppm not as bright. So now I feel better about how much my wc makes a difference. Tank will be a year old in Jan. and I'm starting to get a good read on the water and fish without testing. The big takeaway from all this is how important consistent wc are. Just a few extra days gone on a trip and my reading almost doubled still not that high. At least I know from both of you there are alot more important reasons for pwc.
Thank you both for sharing your knowledge.
Airborne

 

[Andy Sager]

Just a follow up on my new nitrate test. Tap water with and without clorine 0ppm or bright yellow Tank water 24hrs after pwc 0-5ish ppm not as bright. So now I feel better about how much my wc makes a difference. Tank will be a year old in Jan. and I'm starting to get a good read on the water and fish without testing. The big takeaway from all this is how important consistent wc are. Just a few extra days gone on a trip and my reading almost doubled still not that high. At least I know from both of you there are alot more important reasons for pwc.
Thank you both for sharing your knowledge.
Airborne

Yup, people keep trying to find ways around doing water changes but the best thing for the fish is clean water, no doubt about it, just do them.