Flow rate through carbon for no water change system?

[Willbiker]

Hi all

My 1000 litre reef is almost 1 year 10 months old and I'm attempting to stop water changes. I dose major and minor elements and my chateo and gfo keeps my nutrients in check.

I am relying on carbon to remove any nasties in the water and I have a twin reactor for carbon and gfo. I can only achieve a flow rate of approx 30 litres per hour without grinding my gfo up. This means my entire water volume passes through the carbon every 33 hours.

Is this too slow?

 

[AJsReef]

I’m not sure it really matters, as long as you change your carbon regularly. Heck, plenty of reefers use carbon periodically or not at all.

 

[Willbiker]

I’m not sure it really matters, as long as you change your carbon regularly. Heck, plenty of reefers use carbon periodically or not at all.

Thanks AJ . I change it approximately every 6 weeks...is that enough?

 

[AJsReef]

Thanks AJ . I change it approximately every 6 weeks...is that enough?

It’s likely spent/at capacity after a few days, maybe a week. So really you’re running carbon on a 6 week interval. If you aren’t seeing any I’ll effects I would change it. Although personally when I ran carbon I ran it biweekly.

Some use water clarity as a way to tell if it’s spent. Just empty some water into a white bucket and if it isn’t clear time for carbon. Not scientific by any means though and probably anti to what you’re trying to do given your trying to put buckets away with no water changes

 

[Spare time]

Like AJ said, it probably doesn't matter. Most people prefer a slower turnover so there is more time in contact with the carbon but I al not sure how much that matters.

You may not need the gfo all the time, especially if you get your refugium growing well. I keep gfo in a little bag so that if I overdose phosphate or if my nitrate bottoms out and phosphates go up. I toss it in for a day or a few hours in a sock or such then remove it.

 

[PatW]

I think that the carbon will absorb the stuff as it flows through. Once every 33 hours is pretty low flow but it is about 6 tank volumes per week. So that is probably plenty. The problem is that it is hard to tell just how fast you are generating wastes. So it is hard to tell how often your carbon is depleted and how often you need to change it.

I have heard that putting the tank water into a white food grade 5 gallon bucket and looking at it for amber color is a good indicator of impurities in the water. Pristine water should have a slight blue tinge. Anything yellower than that can probably be rectified with carbon.

I would respectfully suggest that you do some water changes. Water changes are a brute force technique but they are a sure fire method of replenishing trace elements and removing any kind of accumulating wastes. You would only have to change about 5 gallons per month to have a reasonable schedule. But it is your system and you call the shots and not me.

 

[Spare time]

Also I wanted to add that I like to rinse my carbon in tap water every 2 weeks to clean out bacteria and gunk. I can also do a chlorine test on it to see if it is still removing something but I just change it out once a month anyways

 

[Willbiker]

I think that the carbon will absorb the stuff as it flows through. Once every 33 hours is pretty low flow but it is about 6 tank volumes per week. So that is probably plenty. The problem is that it is hard to tell just how fast you are generating wastes. So it is hard to tell how often your carbon is depleted and how often you need to change it.

I have heard that putting the tank water into a white food grade 5 gallon bucket and looking at it for amber color is a good indicator of impurities in the water. Pristine water should have a slight blue tinge. Anything yellower than that can probably be rectified with carbon.

I would respectfully suggest that you do some water changes. Water changes are a brute force technique but they are a sure fire method of replenishing trace elements and removing any kind of accumulating wastes. You would only have to change about 5 gallons per month to have a reasonable schedule. But it is your system and you call the shots and not me.

Thanks for the replies! My water quality seems to be excellent. I've not ever seen any yellow tinge so I'm pleased however I've always changed about 5% a week.

I figured if my major elements, trace elements and nutrients are all good and I run carbon......why spend £25 (im from the UK ) per month on salt! It seems like money down the drain...

Would 5 gallons a month really be enough to remove any nasties in the water? Wouldn't carbon do a better job at that?

 

[Screwgunner]

In my opinion if you have corals you have chemical warfare going on . It can't hurt. I run a cup full for two weeks and change.