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Discussion Starter · #1 ·
I know this often comes up and always said, when doing water changes to dose your dechlor for the whole volume of the tank, not just the amount of new water your putting in. But why? Common answer: because even though your only changing X% your still diluting the dechlor by the whole volume. Sounds legitimate right? Well I started thinking about it. Lets say you change 50% of your tank water. I'll assume were starting with the 3.3mg/L chlorine that Prime treats at its standard dose (my chlorine levels actually 2mg/L). So by changing 50% of the tank water were diluting the chlorine 50% to 1.65mg/L. So shouldnt we dose accordingly with a half dose of Prime seeing how the chlorine levels are at half? For example on the bottle of Prime it reads "If temperature is > 30 °C (86 °F) and chlorine or ammonia levels are low, use a half dose." This would suggest that the Prime dosing can be dosed based of actual chlorine levels not necessarily tank volume alone.

Lets say you have a large tank, like a 240G, and are doing a 10% daily water change (automated) - I ask because this is what I am setting up. My levels are already lower than what the recommended dosage of Prime is, but if I am diluting out 24G of tap water with 240G of tank water is there really a need to dose dechlor full strength for 240G for levels of 3.3mg/l when my tank will be closer to .33mg/l (well actually my levels will probably be .2mg/l)? Even if Prime was dosed at half strength that would still be for 5 times the concentration that my tank will actually have. Even dosing at 1/2 that still makes me somewhat concerned. Not to mention that the cost will add up when I'll be doing this daily water change on a 240 and 150 both with sumps.
 

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Some waters have chloramine. Not chlorine. Ask your local waterworks.
Even a little chloramine can kill sensitive fish because they don't dissapate like chlorine. I killed a few rummy nose before I figure out my water has chloramine insteady of chlorine..( I usually let water sit for a few days for the chlorine to go away )
 

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I dose Prime before my water goes in the tank....isn't that what everyone does? I'm sort of confused here.
I think it depends upon One's method. If someone uses buckets--then it would be less expensive to dose Prime only into the new water in the buckets (in theory anyway). If they use a python or some other means where the water goes directly into the tank from the source--Seachem recommends dosing for the entire tank quantity.

But, Again--I think that should really depend upon intent, but Seachem does not differentiate.

HTH
 

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I think it depends upon One's method. If someone uses buckets--then it would be less expensive to dose Prime only into the new water in the buckets (in theory anyway). If they use a python or some other means where the water goes directly into the tank from the source--Seachem recommends dosing for the entire tank quantity.

But, Again--I think that should really depend upon intent, but Seachem does not differentiate.

HTH
I do exactly that. My CRS tanks that get a mix of tap and RO get Prime in the tap water before the water change (I age the water overnight because they're only 10g & 3g) and I only dose Prime for the volume of tap water that's going in. For my 90g, that's just not reasonable so I dose Prime for the volume (a double-dose effectively) after I dial in the temp and right before I stuff the Python in the tank. I've never lost a fish due to water change that way.
 

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Discussion Starter · #8 ·
Some waters have chloramine. Not chlorine. Ask your local waterworks.
Even a little chloramine can kill sensitive fish because they don't dissapate like chlorine. I killed a few rummy nose before I figure out my water has chloramine insteady of chlorine..( I usually let water sit for a few days for the chlorine to go away )
My water uses chlorine, like I said. Most dechlor like the one I mentioned (Prime), are for chloramines as well so all the same still hold true. It doesnt matter if its chlorine or chloramines, if your diluting it by 50% or more than your diluting it.

And FWIW, I am not a newbie asking why its that way, I am just challenging the current thought. If you have a scientifically factual reason why, please post.

As for those dosing their water before it goes into the tank, I'd wager to say more dose it in the tank. Especially on larger tanks. But thats irrelevent, if I was dosing water that isnt in the tank yet, it wouldnt be diluted, and I would dose for that volume.

Yeah I see that Seachem doesnt differentiate... on one hand their directions do say to treat the whole tank but they also say if your chlorine levels are low to use a half dose (well by changing 50% or less of your tank water your chlorine levels are going to be low).

As a side note, my research at one point turned up someone with a large tank doing small daily wc that he didnt even dose dechlor, instead acclimating is tank to very small levels of chlorine that resulted. Since that doesnt seem to be too common, I'm not probably going to try that method.

Just wondering if treating the whole tank is just extra money for the guys selling dechlor. Like I said, if I dose for full tank amount daily, thats a daily 10X OD of Prime for the actual chlorine levels present (well actually higher than 10 since my levels are a bit less than one Prime is intended to treat).
 

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I dose for the water removed but a little more.... I have 2x6' tanks and dosing the full amount would be killer!

I do 50% water changes on them weekly and dose for a 60% water change which comes straight from the tap.
 

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I know this often comes up and always said, when doing water changes to dose your dechlor for the whole volume of the tank, not just the amount of new water your putting in. But why? Common answer: because even though your only changing X% your still diluting the dechlor by the whole volume. Sounds legitimate right? Well I started thinking about it. Lets say you change 50% of your tank water. I'll assume were starting with the 3.3mg/L chlorine that Prime treats at its standard dose (my chlorine levels actually 2mg/L). So by changing 50% of the tank water were diluting the chlorine 50% to 1.65mg/L. So shouldnt we dose accordingly with a half dose of Prime seeing how the chlorine levels are at half? For example on the bottle of Prime it reads "If temperature is > 30 °C (86 °F) and chlorine or ammonia levels are low, use a half dose." This would suggest that the Prime dosing can be dosed based of actual chlorine levels not necessarily tank volume alone.

Lets say you have a large tank, like a 240G, and are doing a 10% daily water change (automated) - I ask because this is what I am setting up. My levels are already lower than what the recommended dosage of Prime is, but if I am diluting out 24G of tap water with 240G of tank water is there really a need to dose dechlor full strength for 240G for levels of 3.3mg/l when my tank will be closer to .33mg/l (well actually my levels will probably be .2mg/l)? Even if Prime was dosed at half strength that would still be for 5 times the concentration that my tank will actually have. Even dosing at 1/2 that still makes me somewhat concerned. Not to mention that the cost will add up when I'll be doing this daily water change on a 240 and 150 both with sumps.
Ok, let me say this:

I have and still do use buckets. I have a python and rarely use it these days. I have and do use Auto and Semi-auto WC systems. I do and have used Prime. And I have used other dechlors. I Always overdose dechlor. When I use/d Wardleys I would add 40 drops to a 5g bucket that recommended 25 drops. Why? Its just me--I just want to neutralize any chlorine/chloramine and forget about it. Same story when dosing directly into the tank--except I normally overdose for the amount of water going into the tank--not necessarily the whole tank volume.

When I dose in reference to Ammonia and/or Nitrites (influx of Feeder fish) I dose/overdose based on entire tank volume and experience.

Why do we dose for the entire tank for WCs? I don't know and I don't Think that its necessary, but that's what we tell each other to do and that's what most/many do--IMO. And in reference to Prime: That's what the Manufacturer recommends.

I don't understand the "Diluting Theory" at all. I put in X-amount of dechlor to deal with X-amount of chlorine/chloramine--not sure what "Diluting" has to do with that. I have always been more concerned with the dechlor not getting "Diluted" or spread around the tank quickly enough, but that has never seemed to actually be an issue. Just my paranoia.

In reference to auto-dosing Your larger tanks MO and ME is this:

240g: 10% WC=~24g. Just dose a cap full=5ml and You should be fine. Prime is consumed--over time--by the bacteria. But it is available in the tank for 48 hrs. So, if You auto-dose 5ml(=50g) 1hr prior to your WC it should be in full strength and spread throughout the system by the time the WC begins.

Why Seachem or anybody else recommends dosing for the full tank volume? I don't know. It doesn't really make much sense to me, except to sell more product. But, left alone, plenty of people really aren't very bright. So, these companies also need to protect themselves against the morons running around. "I used Your product as direct and all my fish died--and its YOUR Fault!" When in actuality--it was the users fault. When I use a Seachem product that doesn't work as its suppose to--I go to their forums and ask what am I doing wrong. The only product of theirs that I've used that I currently think is pure garbage is the pH Alert. The rest work as directed. So, from Experience, and what I like to think is common sense--I use the products as I see fit and things work out well.

Its a Good Question and a Fair Question, and, personally, I can only offer information based upon ME and what Seachem has offered. With what Seachem has offered--Full tank dosage still doesn't make sense. I assume that Prime splits the chloramine into ammonia and chlorine. Its available in the system for 48 hrs. In that time, I would assume: The chlorine would dissipate and the ammonia would be consumed by the bacteria. Maybe I'm missing something......:tongue:

I just posted this question on their forums:

Dosing Prime....?
 

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Interesting question -which I don't have an answer to.

I dose Prime for tank volume in the smaller tanks - likely because it's easier dosing 1 ml in a 10 rather than trying to cut it smaller. In the larger tanks I dose just for the actual volume of tap water added.
The other reason for me is that once you have a whole tank of fish die after a water change you get the fear of it happening again - it's hard not to dose the 'recommended' at that point. My water company likely added more chloramine 3 Springs ago - they will invariably do this without warning as well.
 

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I dose a few drops of Prime for chlorine (no chloramine in NYC) with every bucket of new water change I do. I only dose Prime directly to the tank water after a gravel vacuum, filter media rinse, or major plant pruning (which only occurs every Month or two) since I notice a brief spike of Nitrites soon after those events.
 

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The reason why you dose for the entire tank volume when using something such as a python is because something like Prime takes out nitrites, nitrates, chlorine and chloramine i believe. So dosing for the entire tank volume will ensure that there is enough to go around. If you dosed for only the volume of water being changed, Prime may be used up taking care of the nitrites and nitrates and not take out the chlorine/chloramine.

If using buckets and adding Prime to buckets, you are essentially dosing for the 'entire volume'.
 

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Hope you dont mind me asking a question in your post. I think it is relevant.

When i am adding my water back into my tank after a water change is it safe for me to add tap water to fill the tank back up and then add the dechlor solution once the tank is full ?

If not, then could i drain the water i am taking out to do the water change and add the dechlor solution to the water still in the tank. Then add the new water straight out of the tap ? The dechlor i added will take care of the new water because the old water wont use it up since it already has chlorine removed right ?

I ask because my tank is really close to my sink which has an extendable faucet so i would love to be able to just turn it on and fill er up rather than using buckets.

Any thoughts ?

James
 

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I've done it that way, with a two gallon guppy tank... they didn't seem to care THAT much. All my other tanks are too far away from any faucets for me to be able to dump in water without using a bucket. (yes, this DOES get annoying with the 50gl, but whatever. it's good for my arms until they start to feel like they're seperating at the joints...) And I've always dosed in the bucket.

I actually always wondered how people with the auto water changers did it... I guess if they dose the tank after the water's in it, that must be how it's done... You'd think that would wreak havok on their filters and such, though.
 

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Discussion Starter · #20 ·
I actually always wondered how people with the auto water changers did it... I guess if they dose the tank after the water's in it, that must be how it's done... You'd think that would wreak havok on their filters and such, though.
I am thinking that most with auto water changers use a reservoir with R/O unit.

As far as wreaking havoc on filters, dont forget how diluted the chlorine is. Those doing daily auto changes / top off are usually changing around 10%. So that drops the chlorine to 10% of its concentration at the tap , combined with the fact that it will off gas pretty fast(assuming they arent using RO or some other method to have already removed chlorine). So thats like .3mg/l chlorine for most folks, and thats without any gas off yet so that number will probably be even lower. Not sure at what concentration chlorine becomes insignificant??? For those changing 50% in one swipe, well thats still over a fairly long period, like say 30 minutes. When doing it manually I add the dechlor first and its fast acting so as the new water is being added some of the chlorine is already being removed before it even builds up to the 50% concentration.
 
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