Newly Cycled Tank - Next Steps...?

@Byron, I’ve tested the tank and the RO water using the 2 minute shake method, both sets of water are registering the same result, but it is now at the 40ppm level.

I’m getting my RO water from my local Maidenhead Aquatics, I’m making the assumption that this should be a good source and for all of the fish they keep, probably within good parameters..?

Do I assume as I’m getting the same reading for the tank and the RO water that the test is “off”...

Can I risk putting a fish into the tank?
Its reasonably well planted including two new Limnopila heterophylla, which Imthink I have read are very good for absorbing Nitrates?

Brita filters don't remove nitrate - or at least ours didn't when we had one. They remove GH and KH, and chlorine; and they reduce pH as they swap the hardness minerals for hydrogen ions.

RO water should remove everything, including nitrate. The less effective equipment doesn't remove absolutely everything, they do leave a bit behind. But even the least effective should substantially reduce everything.

Does your branch of Maidenhead Aquatics sell pure RO, remineralised RO or do they give you a choice? Though even remineralised should not contain a lot of nitrate.

What does your water company's water quality report give your nitrate as?



Something I have noticed from your photos - are the tubes the ones that came with the kit? My tubes look a lot longer than those. And they have a white line round the middle at the 'fill to' mark.
I got my camera out to take a photo and the battery was flat. So I'll have to give you the measurements instead. My tubes are 8.3 cm long without the caps and 1.2 cm across. They take 5 ml water to the line which is 4.8 cm from the bottom of the tube.

@Essjay - no, they aren’t the original tubes, they were glass and came out of the kit broken. So I’ve bought new ones. I use a syringe to measure the 5mls.

I asked for NON-remineralised RO (having made the rookie error of saying yes please the week before ?).

Portsmouth Water website has Nitrate (mg/l NO3) as 31, 33.8 and 36.5 as Min, Mean and Max...

The tubes are not the problem, then. It had occurred to me that if you were using say 3ml water but the number of drops for 5 ml, it would give weird results.
The RO water should read zero, or at the very worst somewhere under 5.
Your tap water should give a reading just a tad less red than the 40 ppm colour if it's the same as the water company's level. Using their figure, the 50/50 mix should have a nitrate level half way between the 10 and 20 colours.

Are the bottles still in date? It is not unknown for some sellers to have out of date stock.


I am running out of ideas.......

@Essjay - yes to in date (exp 01/2026).

If you run out of ideas what on earth am I supposed to be able to do ?‍?

NannaLou said:

@Byron, I’ve tested the tank and the RO water using the 2 minute shake method, both sets of water are registering the same result, but it is now at the 40ppm level.

I’m getting my RO water from my local Maidenhead Aquatics, I’m making the assumption that this should be a good source and for all of the fish they keep, probably within good parameters..?

Do I assume as I’m getting the same reading for the tank and the RO water that the test is “off”...

Can I risk putting a fish into the tank?
Its reasonably well planted including two new Limnopila heterophylla, which Imthink I have read are very good for absorbing Nitrates?View attachment 135191

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I can't offer more on the nitrates in those water sources, so will leave you with essjay. Tank looks lovely, if we could just sort out the nitrate issue. Fish are affected by nitrate above 20 ppm, to varying degree depending upon the species, level and exposure time.

Most aquarium plants prefer ammonia/ammonium as their source of nitrogen, and they can assimilate quite a lot of it, faster than the nitrifying bacteria. Most do not take up nitrate unless forced to, by a lack of ammonia/ammonium in balance with light and other essential nutrients, but this is something that is rare in a fish tank, ammonia/ammonium shortage. Plants have to convert the nitrate back into ammonium and this is extra work/energy. Their rapid assimilation of ammonia/ammonium means no nitrite, and thus no nitrate down the line. There are a few species that have been shown to take up nitrate equally or over ammonium. The results of one study (cited in Diana Walstad's book, Ecology of the Planted Aquarium), does not have Limnopila heterophylla in either group so presumably this species was not in the study.

All I can suggest is to forget nitrate and go by ammonia and nitrite to see if the water is safe for fish.

Using a 50/50 tap/RO mix should get nitrate down below 20 ppm and the plants should take up all the ammonia so nitrate should not be made in the tank.
The fact that the RO water is showing the same nitrate result as your tap water means something odd is going on - either the tester is not working as it should, or MA sold you tap water instead of RO Or their RO equipment membranes need changing.

You could try taking a sample of your RO back to MA and ask them to test it. If they come up with zero, or very nearly zero, you'll know it's the tester. If it shows high, tell them it's the RO water you bought from them on 'this date' and ask them why it gives that reading; and suggest they test the RO water they have there when you go.

@Essjay and @Byron, I really very grateful for the time you are taking in trying to help me sort this out - and even with your help it’s getting increasingly closer to housing a hamster!!

I’ll take the water back tomorrow and ask them to test it and see what that returns.

do you think it would be reckless to try another Betta if their results are the same as mine? If their results are less than 5ppm - I’m assuming that will be a green light?

If their results are the same as yours, there's something not right with the RO water they sold you. It should have virtually no nitrate. Even if their equipment is poor quality, it should still be well under 5 ppm. But if their test shows the RO water they sold you has high nitrate, either they put tap water in the container by accident, or their equipment needs some maintenance.

That's why I suggest if their test is high, asking them to test the RO water they have for sale. They could always try to make out that what you've brought back isn't what they sold you, but if the RO water that they haven't sold yet is high, it's their equipment at fault.


But if they test your RO water and it's virtually zero, it's your tester, and you can buy a betta.

@Essjay - your last sentence may just have saved my sanity and evening ?. I’ll keep you posted

@Essjay,@Byron - I have a fish ?!

I took the RO water and a sample of tank water to Maidenhead aquatics, explained my nightmare and they tested both sets of water while I watched and waited. RO water 0 ppm of Nitrates and the tank water was 15 ppm!

The 3 youngest grandchildren have chosen a blue Betta and wait for the name....BLUE!! ??

He’s lovely and I’ll take some photos later.

He’s still in the tank with no lights at the moment, but he’s looking for food and spitting out sand! Will he want something to eat this evening, or shall I leave him until tomorrow..?

That's great

Leave him till tomorrow - fish don't need to be fed every day and he'll be stressed from the move. Don't forget to take photos when he's settled




Looks like it's a problem with your tester. Given the level in your water quality report, 15 ppm is what you would expect from a 50/50 mix.

Good morning ? I think I’ve got a very happy Betta ?

I‘ve given him a little bit of Betta pellet for breakfast (they are tiny - like fine sand) so couldn’t count the 2-3 pellets that I’ve read is about right, and my scales showed a huge amount for another ‘recommended’ 1.8g. He’s had a tiny little pinch and has hoovered it all up, on the basis he’s better under than over fed I’ll do the same this evening and will adjust as I get to know him better.

I’m worried that when he gets to one specific point at the right hand edge of the tank he is flaring, I’m trying to work out if he can see his reflection in the glass, he’s not doing it at the other end..? Is the a way to stop the ‘reflections’..?

He‘s spending much more time at the front of the tank this morning (I’m hoping he will note that this is the feeding corner and I’ll get to see lots of him!) and I’ll try and get some photos later ?

He may be flaring at his refection, or possibly something outside the tank?

You often read to put matt black card against the tank but that never worked for my bettas, they could still see their reflection. Another alternative is to put some decor against that side of the tank to block his view.

NannaLou said:

Get a fish Mum, it’ll help your blood pressure Mum...hhmmppffff...

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Who said this?! I'd check that they aren't secretly trying to make it worse!