Dosing carbon, time of day ?

[oceanarium]

Hey all you dosers how often and when do you add your carbon dose?

I have had all mine on an auto doser GHL units adding the required volume on an hourly basis.

My big display has always had that slightly misty look when looking down the 2 meter length. On the odd occasion the carbon doser accidentally emptied before I got around to refilling it the water clarity difference was quite obviously better.

The old GHL died so trying a new 5 way jebao to add my supplements. The Jebao allows me to pick the actual time of day the dose goes in so decided to trial a larger dose late in the day and the rest as a smaller volume in the morning. All done in two doses for the same volume I was doing previously over the 24 hours.

Results are I now have that crisp clarity of the water during the lights on period.

I have not seen much reference material so far as the best time of day or frequency of dosing so looking for opinions.

Pete

[Rod the Reefer]

What are you dosing Pete?

I'm dosing vinegar and have set it up to dose during the day and not at night to try to keep the pH up.

Rod.

[oceanarium]

Yes I was concerned about reducing oxygen at night.... though after all it is a display so i want it to look at its best during the day.

So far as what am I dosing I call it my sweet and sour sauce. I react vinegar with aragonite to create a complex of acetates Ie Mg acetate, Ca acetate, Sr acetate, then add some sugar.

Pete

[Rod the Reefer]

Wow, sure you're not cooking up Milton the Monster?

Rod.

[oceanarium]

It has been working well for a long time and I did reduce the need for elemental additions quite noticeably.

I am not so sure now the time of day is the key or if it is more so breaking up the dose to break a 24 hour cycle of bacteria in the water? I don't see any sort of change in clarity after the morning dose. Certainly enjoying the crisp clarity of the display, the tank has never looked so good.

Ph is also very good before lights come on at 8.4. Phos tested low as well.

Is there an accepted time frame after a carbon dose for bacteria to bloom in and for how long?

Pete

[pebbles]

Good morning folks,

Interesting topic.

Is there an accepted time frame after a carbon dose for bacteria to bloom in and for how long?

I posted this question to RHF a few years back. His answer was about 2-3 hours after feeding, depending mainly on temperature. I tried this but it didn't really work for me as I feed all day long.

I did try the once a day dose, was most effective late in the day, less effective in terms of water clarity early in the morning. Not sure, but I think how and what you feed has a major impact here, and how well tuned your skimmer is.

[Onsan]

In any biological system, consistent input/outputs are always the ideal for producing stability.
I would have doubts about basing dosing 2-3hours after a feed, I'm assuming he's based this on anticipated ammonia waste from digestion. From my aquaculture days, prawns would take around 4 hours from feeding to fill their (very simple) digestive tract and begin excreting. Fish are larger and have a more complex system and I would expect the time to be inherently longer. Add to that, the ammonia requires nitrification before it can be denitrified (ammonox excluded).
I guess there's some basis if you're dosing acetic acid like Rod, but I don't think that it really would have that much of a definable impact though, the acid dosed would be more or less instantly neutralised by the alkalinity and have no bearing on the pH like CO2 does irrespective of alkalinity. All that you should see is a depletion in alkalinity, not pH.

Chemically, reaction rates can be limited by a number of physical factors but ultimately any limiting reagent governs the completion of the overall reaction. If carbon is limited, nitrogen levels increase until sufficient carbon has been added to allow the completion of the reaction. By dosing intermittently, you are promoting the fluctuation of nitrogen levels and driving bacterial populations through a boom or bust cycle. In most cases, so long as the cycles are not too extreme, I would expect that bacteria populations would simply adjust their activity level to suit, however if the periods are too long or too high/low, the stress can result in a limited die off, this ultimately results in the release of stored nutrients into the environment, particular phosphate.
I don't think any general reef system is going to have an issue with DO levels dropping to an extent to be concerned about, if anything, intermittent dosing is more likely to exacerbate any potential excessive DO demand by stimulating a burst in activity or population of bacteria, causing a sudden increase in demand.

When we dose carbon in wastewater treatment plants, the dosing is always applied continuously and at consistent levels, we do monitor the systems ORP to optimise the processes but our chief aim is to ensure stability and consistent nutrient reduction, fluctuations are generally bad news.

All goes back to the simple adage, nothing good happens fast in reefing.

[oceanarium]

Onsan, if I read Angie's post right she was indicating the bacteria bloom 2-3 hours from feeding the carbon to the bacteria, rather than the fishes?

I should also add when I adjusted the carbon dose to go in twice per day I also adjusted the nitrate dose to go in one hour earlier so it would mix with the water thoroughly ready for the following carbon.

Further observations I have been testing PO4 every few days and have reduced the total carbon dose each time as the PO4 remains below my desired 0.03. So I am using less product for a better result?

I also cleaned the glass today, it was hazy as it normally would be after a week usually this would be a haze of algae. Today it was a bacteria biofilm I would not normally have seen.

Water is still crisp and crystal clear.

Pete

[Onsan]

oh, I see, missed that.
So what happens after the bloom of bacteria? If they die or are stressed, assimilated PO4 becomes available again. As the bulk of bacteria are benthic, how effective is filtration at removing phosphate gorged bacteria from solution? I would think cleaning your glass of film helps that somewhat.
I don't think you're necessarily dosing less and getting a better result, maybe more accurate to say you're being more efficient in your dosing?

[oceanarium]

That was what I was wondering myself is the bacteria becoming more available for export in some way?

Weekly I do a major maintenance change activated carbon, siphon any detritus, clean glass, test water parameters etc. After last weeks day the next day that misty look came back for 24 hours.

Other than that its been crystal clear and the glass looks pretty good too. Maintenance day today again so will be interesting to see what the tank looks like tomorrow.

I moved another system onto the twice per day regime (same volume of carbon dose) and noticed some of the sensitive corals like Chalice starting to lose colour. I have added nitrogen as the system was reading absolute 0. Previously this had been a stable low N but not 0 system and chalice had been booming.

I have changed this second system because it can get bacterial clog in carbon filters and bio matting on some over flows, just to see if there is improvment with that.

Pete