back to back PWC question

[sobersteve323]

I'm currently fishless cycling and I'm pretty sure I'm done. However my nitrites and nitrates are both through the roof. I've done 3 ~90% PWC over the last 3 days and I still can't read my neon purple nitrites and nitrates are a constant red.

To save some $ and prime, is it possible to do back to back PWC without dechlorinating each time? Of course my fluval is turned off while doing the PWCs. It just seems like a waste of prime to dechlorinate water that's going to end up watering my garden!

 

[NoMoreGoldFish]

How big is your tank? It costs like 10 cents to treat 30 gallons of water.

 

[ChelleBells]

Wait... If you are doing a fishLESS cycle, why are you doing PWCs?

 

[ChelleBells]

Also, if you don't use prime, you'll end up killing all of the bacteria you're trying to grow. Cycling your tank is an exercise in patience for sure. Stop doing PWCs and just continue to add ammonia daily until your tests are zero. (or near zero for the 'trates) if those levels are through the roof, you're not done yet.

 

[FastFly67]

I think Chelle might have it backwards. If your nitrItes are thru the roof, you're not done yet.

 

[ChelleBells]

Lol! Not backwards, just poor wording. Oops. I meant if the levels you mentioned in the op are through the roof (both nitrites and nitrates)

 

[librarygirl]

You're not done until nitrites are zero (blue tube) but you could be close. How long have they been high? If you've done some large water changes and they are still purple you have a lot of nitrite in there. I'd keep doing pwc to get them down to a readable level on the chart (<1), then dose ammonia only to 1 for a few days to let the bacteria catch up (only dose that low for a few days and then go back to your usual dose). The nitrites might climb again quickly after all this but that's normal. you should be close. Just remember you aren't done until nitrites are blue too.

To answer your questions you cannot change water without a dechlorinator; the chlorines and chemicals in your water will kill all the beneficial bacteria you are growing and then you'll be back at the beginning. If you're using Prime it should be lasting you quite a while. How large is your tank? How do you replace water? If you replace water from the tap with something like a Python or Aqueon changer then you want to put enough Prime for the whole volume of the tank into the tank first then refill; I think a whole capful treats 55 gals so make sure you're just not using too much, that might be your issue of why you're running out so fast. If you use buckets, you could still either treat the whole tank and then dump the water in or treat the buckets (read the bottle but I believe 2 drops treats 1 gallon).

 

[sobersteve323]

Sorry for being light on the details already had a a thread about my cycle. Long story short: cycling for 7 weeks, had massive white hair algae bloom. Most was sucked into my filter, decomposing and has been releasing ammonia in addition to the single dose I placed originally at the start.

I understand the concepts behind the nitrogen cycle. I assume I'm done or near done because at one point last week I was able to get all the readings low enough to measure. Nitrites would rise off the chart and nitrates would rise over 10ppm each day.

My tank finally started producing less ammonia to a point where the bacteria are now able to convert an additional 4ppm of ammonia along with whatever algae may still be decomposing. However like every fishless cycle article states, including the ones here, the nitrite to nitrate bacteria are slightly behind the ammonia converting ones since there weren't nitrites to consume at the start of the cycle. The guides also state that there is no problem doing PWC during a cycle to lower nitrites and nitrates down to readable levels as there are a negligible amount of BB in the water itself.

Even though I still read nitrites in my water column, my reasoning leads me to believe that if I'm adding over 10ppm of nitrAtes every day, I must be converting that much ammonia and nitrItes at least (you can't create something from nothing). But since there is more ammonia converting BB, there is a backup at the nitrite stage of the cycle.

In addition, my original question stems from reading other user methods of doing PWC with a python. Some dose the full dose in the beginning. Some dose half first then half during. Others dose after. Even though there is BB on every surface in the tank, most of it is in your filter. I've read of users dumping untreated water into their tanks and not realizing it until later with no negative effects on their biofilter. I wouldn't be doing this obviously as the filter is off during PWCs.

Sorry for any typos, I'm using my phone. Crazy lightning storm keeps knocking the power out!

 

[StuG]

I'm certainly no expert, but I have to disagree with your summation about the cycle being done. Nearly done, yes. Indeed the nitrites do lag behind, but they still need to be being converted to 0 within 24 hrs for the cycle to be fully complete.
Also, while water changes can be useful to bring readings within reasonable levels, if you are doing them very often, then you as well just fish in cycling.
All of this is just IMO of course.

 

[jetajockey]

Even though I still read nitrites in my water column, my reasoning leads me to believe that if I'm adding over 10ppm of nitrAtes every day, I must be converting that much ammonia and nitrItes at least (you can't create something from nothing). But since there is more ammonia converting BB, there is a backup at the nitrite stage of the cycle.]

Hi Steve. It doesn't necessarily work that way. I don't know the exact details of the ammonia => nitrite => nitrate transition but it seems like sometimes there is a lag time between them, so you could still have nitrites popping up even when there isn't any ammonia added to the tank. This is just an observation though so I don't know how much merit it has.

 

[maxwellag]

What test kit are you using? If you have done 90% pwcs every day for three days, the nitrate and nitrite should gotten lower...

 

[sobersteve323]

What test kit are you using? If you have done 90% pwcs every day for three days, the nitrate and nitrite should gotten lower...

I'm using an API kit. Last week I could zero out the nitrites and nitrates if they were too high to measure but its the last few days I've been unable to bring it down before its unreadable.