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Nitrates always zero - Has my Fishless cycle stalled? pls help...


5 Dec 2012
Weston Super Mare
260litre Fluval Vicenza
Fully planted
2 x T5 with reflectors
C02 through Atomiser
Dosing EI and liquid c02
2 x New Wave Circulation pumps

My tank completed a fishless cycle 2 weeks ago after a re-scape, fish have been added gradually over the past couple of weeks and unfortunately we have lost a few fish over the last week including 3 x dalmation mollies which I found at the bottom of the tank yesterday.

Water parameters are
PH= 7
Lights on at 5pm, of at 11pm so 6hrs photoperiod
C02 on at 3pm and off at 9.30pm (JBL m oo1 reg)
Good flow as have 2 x Newwave circ pumps
filter is fluval 405 topped with purigen
Critters are approx 15 Yamato shrimp (all ok), 15 rummynose tetra, 2 remaining dalmation Mollies, 2 small bristlenose, 4 x otos, 6 x harlequin rasboras and 4 horned snails.

i'm concerned that my nitrates have completely gone and I have lost my cycle, I also have staghorn growing too, but don't understand why I have no ammonia if my cycle has been lost? does this make sense, just trying to reason why I have algae and a few fish losses,
I do weekly water changes of approx 45 litres which will be each Monday so one due tonight, this follows my 5 day EI dosing Macro and Trace routine, co2 is at a good level with drop checker green.
Dead fish have not shown any signs of disease etc and were totally fine Saturday evening, we popped out Sunday and when we came home 3 were dead, also lost 2 rummynose tetras on separate occaisions, again no visual signs to indicate why.

I'm worried I have lost my cycle, as a week ago which was 1 week after my fishless cycle completed I carried out a water change, and also did a quick filter maintenance, the 1st since cycling started, only lightly rinsed the ceramic media in the removed tank water and lightly squeazed the sponges, would this have been too early and could I have ruined my cycle? I have no Ammonia nor Nitrites though, using API Master Test Kits and testing each evening.

So I have 2 concerns, mainly my fish deaths and secondly the Staghorn growth.

Any suggestions would be welcomed, thanks...
Cleaning out the filter could have easily damaged the bacteria population which would have been fragile anyway as a new colony. I wouldnt touch a filter for at least a couple of months aside changing floss if using it to allow time to mature.
Have you been home all day during co2 to see how all the fauna are behaving through the whole cycle?
Additional water changes are nearly always step one.
Filter, I changed the floss as you say and possibly shouldn't have touched the sponges, I don't understand though if I have upset the bacteria why I see no nh3 nor n02 is this still good?
c02 wise, I'll be honest and say no, not the complete on off period,my wife is home and watches but I've only been able to see the period after 6pm due to work etc, I've so far not noticed any gasping or odd behaviour.

I presume I'll need to carry out more frequent water changes to help with stubborn outbreak, my net water volume is about 230 litres taking into account substrate and landscape, I've been doing weekly 40 litre changes, should I be doing 115 litre changes twice a week which would be about 50%? This would take me some time but if it's necessary I'll do it.
Yeah, and your dependency on test kit readings are killing your fish.

Thanks Clive, I'm not one to question your knowledge, I'm looking for some help and guidance and from you it would be welcomed, I am however, more confused than before and unsure what I need to start to put in place to put things right, should I not use the test kits then?
With lot's of plant's ?,,I would not be surprised at near zero reading's for ammonia,nitrates,for plant's are very good at assimilating them.
Seem's a fair bunch of fish for new system,and considering that no other fishes other than the mollies have died,, I would maybe contemplate that water does not have hardness that livebearer's thrive in. (10 /12 DGH)
Agree with leaving filter material alone for a few week's, feed fish sparingly, regular weekly 50 % water change.
That's a heck of a lot of fish to add straight off to a new tank.

Test kits can be useful checks, but they shouldn't be followed blindly as they're not perfect.

You don't mention about your CO2 monitoring, is your drop checker ok?

From doing a fishless cycle your filter will have a low volume of established bacteria, the usual approach is to slowly build up the fish volume over time so that the bacteria colony can grow to accomodate the increased waste levels.

Your staghorn algae could be a sign of insufficient nutrients, although that seems odd if you're dosing EI. Any reason you're using LC as well as CO2?
C02 bubble count is currently 3 bps and the drop checker is green from start of photo period, it's not quite lime green and certainly never yellow, using a pre mixed kd4 solution. Drop checker is currently placed in opposite diagonal corner to atomiser and about an inch from the substrate. I can see the c02 bubbles clearly and have positioned the 2 powerheads to give a good flow, plants have been in for 8 weeks now and have been trimmed twice to allow sufficient flow so not to restrict dispurtion of nutrients.
substrate used is Columbo Nutri Base topped with Unipack rinsed black gravel, I'm currently basing my ei solution mix on tnc's calculator based on my full tank volume of 260 litres, making up 1000ml of solution each forboth macro and trace, dosing 130ml on the reqd day. Maybe due to my high volume of plants I should increase the levels?
my tap water has a ph of 8.2 so was advised not to purchase MgS04 as I already had hard water, I use prime as a declourinator. Should I be adding more nutrients and also including Magnesium Sulphate?
Oh sorry I forgot about my reason for using liquid o2, prior to my re scape, the tank was partially planted with pressurised c02 and ferts used were Neutro + purchased from one of the sponsors,I was advised to use Neutro cO2. in conjunction with these ferts,since the re scape and changing to ei solution, I have just continued to dose 5ml of Neutro C02 daily, please can someone confirm if this is wrong.
Seems strange you have no nitrates at all. I dose EI and at the end of every week (before I do a 50% change) the nitrate is 45ppm.

Another point, my tank has 140 litres in there and my bubble counter now is 5 bps plus. Too fast to count.

Odd thing to say, but are you doing the nitrate test correctly? It's a pain in the bum one that one. Test your tap water too. See what's in there. I like test kits. They are very useful in my opinion. Maybe with me being an analytical chemist lol
Martin, testing the same way as when I wad still cycling and then I was seeing both nitrite and nitrates, it's this odd thing that's got me worried.
Ian, I believe Martin doses daily then at the end of the week when he us due a water change he has built up nitrate to the value he mentions.

For an accurate analysis of your water coming from the tap visit your water supplier website and take a look at what you put in at water change. In particular, although you have hard water, check to ensure it is made up of both calcium and magnesium, otherwise you may need a touch more Mg. Once I know what goes in from the tap I don't use test kits as the type readily available to us generally give bonkers results. (eg test you tap water then compare it to the accurate water quality report from your provider)

Are your plants actively growing? new leaves and roots forming, pearling oxygen, etc...if so then that's a positive sign for the future.

Overall I'm guessing there hasn't been enough time for a sufficient bacteria population to handle the fish load and am pointing my finger at ammonia here.
ps what substrate are you using? Not sure I saw...

Good luck with it all!
Does seem a strange situation. If your cycle had stalled, surely the plants you have would not be able to remove all the ammonia produced by your fish. You would see some on your test kit.

You should deffo be seeing nitrate. Can't see your plants consuming it all either.

This is a head scratched.

Any expiry dates on the test kit reagents?
Found the remains of my smallest bristlenose, hidden behind large piece of bogwood in amongst the base of plant stems, not nice, only bones remained so I think I've found the reason for my recent Mollie mishaps and staghorn outbreak.
I tested when I got home and nitrates were off the scale, api test was a deep cherry red so as these were zero last night I have done a 130 litre water change and removed hardscape until these were found..
so another change tomorrow night due but hopefully I'll get to bed before 2am.
Ph still 7, no ammonia no nitrite, just a massive nitrate Spike, I haven't added anything to the water since my last macro dose last Friday night, only small amounts of fish food, no ferts, nothing, this large piece of bogwood is like a small cave, can only be picked up with two hands and the bristlenose always live in there.
test kit is not out of date.
hopefully this should settle down again now, more water changes to do though to be safe.
Tested tonight and nitrates were still about 90ppm, couldn't understand why there was no change since my 50% water change.
I didn't believe it was true so tested tap water and that was 50ppm.
I have a new test kit, re tested and the tank water is about 5ppm, I double checked and it is only 5! Yay.
Martin mate you were right.
so I've done another 130 litre water change, cO2 just gone of and plants are pearling.
fish seem happy too.
so not to rest on my laurels I'll continue water changes every 2 day's for the next couple of weeks.
thanks everyone for all your input, I'll be setting up tapatalk soon so hopefully load a couple of pics soon