Effects of Dissolved Organic Compounds

[John N.]

Please discuss and comment on Cecil Griffith's Dissolved Organic Compounds Explained here.



-John N.

[plantbrain]

This was a good article talking about something that's rarely discussed.
One aspect that was overlooked was in the newly set up aquarium.
DOC in this case is good and you want some to help start the biological cycling. Not too little and not too much.

New tanks typically lack carbon, many aquarist do not think about this as it's not a plant nutrients really(Plants use Dissolved inorganic carbon - DIC).

But lack of reduced carbon can limit the growth of bacteria a great deal.
All those folks adding NH3 to cycling their tanks would be better off taking some mulm from a filter sponge and squeeze it a few times into their new filter and then start adding NH3.

Or better yet, add plants will leach organic carbon regularly.

Regards,
Tom Barr

[defdac]

But lack of reduced carbon can limit the growth of bacteria a great deal.

Yes that was one thing I thought about when I read the article. It was like all DOC always was bad, when it isn't. Too much is bad though.

Knowing how much is bad comes with experience:

I have completely stable CO2-injection (1 bubble/sec, never measures pH) and the same PMDD-dosage each week. If the pearling from plants diminishes I know there is nothing wrong with light, CO2 or nutrients. It's to much mulm/DOC/POC, and most of the time it's inside the canister. Rinsing it usually brings back the pearling instantaneously.

[plantbrain]

Yep, it's also a decrease in flow rates inside the filter, exchange to the roots,
and O2 demand from all the bacteria trying to mineralize the OM.

Too little or too much.

You can certainly see significant differences in the tank by varying things here. But you need a lot of loading to get a good treatment to see such differences, if you have a very low loading on a tank, then you'll never see this.

A good argument for a moderate to low bioload tank if you want to reduce work.

Regards,
Tom Barr

[Pat7676]

Good article enjoyed reading it.

[John N.]

When you have too many dissolved organics building up does this lead to "Old Tank Syndrome" or is this something different?

-John N.

[JDowns]

Great article.

I would like to take it a step further and try and link algea to buildups of OM. This is actually good timing from reading through this thread ( UK Aquatic Plant Society Forum • Login ) and linking some notable personel experiences.

Now bear with me since I am not scientifically minded, and I'll need those with more experience to piece together the whole picture.

First experience - GSA.

This is an algea that has been the most difficult for me to curb. Algea articles and others experiences have linked this to low PO4 levels.

I started adding 25% more PO4 to my EI dosing routine and noticed a slight decline in the occurance of GSA, and a slight increase in pearling. Now my pearling has never been what I would call extreme, so obviously I've been limited somewhere. I then added 25% more PO4 with no noticable difference in pearling or GSA occurance.

But I did notice a difference in CO2 levels. Now I monitor with a drop checker so this has to be taken into account. Previously my drop checker would consistently and gradually towards the end of the day progress from a bright green to a yellow/green in color. My initial thoughts were that I had adequate levels of CO2. But with the final additional levels of PO4 I noticed my drop checker was actually declining in CO2, a darker green in color at the end of the day.

I then upped my CO2 to levels over the course of a few days where the fish were not in stress and there was no longer a decline, and the results were dramatic. I noticed a serious decline in the amount of GSA on the glass and Anubis/Crypt leaves, and serious levels of pearling that I have never had before. Also the amount of haze (what is the whitish/grey haze that builds up on the glass?) that would buildup on the glass was reduced. Now I've also noticed that if I miss a spot of this haze and leave it. That is the first area that GSA will occur.

Plants are now growing faster , more robust, and with better coloration.

Now I also need to note that GSA wasn't an initial problem. I can correlate the increase in GSA with the increase in plant mass, both in mass and height. Which more than likely resulted in the limitation of PO4 to begin with, and the decrease in CO2 uptake (??).

Second experience - Thread like algea's

There are two major spots in my tank that are the most tedios to clean. The overflow box and the backside of tank behind the taller plants. I noticed if I neglect the overflow box, the outside glass would get covered in a whitish/grey haze (once again ??). If I get way to lazy I can notice tiny hairlike threads starting to appear on the glass(done that and learned my leason). Not long after I would have a breakout of hair algea. I've since learned to thoroughly clean the backside of the tank, scrape completely prior to water change then vacuum out the waste, and simply blackening out the overflow box and no more thread algeas. I think thread algeas are just opportunistic in where they end up and become visually apparent. The most common being on plants in high flow areas, where they get caught up in.


Third experience - BGA, Diatoms, Clado

About six months ago I went through a phase where I wanted all the equipment out of my tank. So I removed all powerheads, which were adding circulation, filtration, and biological, to add external pumps and tie them into my loc-line system. Well the wild hair in me decided to pull it all out prior to purchasing the pumps. Go to my local LFS's and they are all out of the Mag Drives that I wanted. Now a wiser person would have reinstalled the powerheads until they were back in stock in the three days that it took. An even wiser person would have done additional spot cleaning in the now multiple dead flow areas that were building up copious amounts of debris from feeding 50+ cichlids three times a day, and already unbalanced system. The result was not all that surprising. Multiple patches of BGA and diatoms appeared almost instantanously across the substrate in the areas of built up OM. Two areas spawned clado that only a complete tear down of the tank solved.

Now I think and I have to agree with the posts in the UKAPS thread that algeas can be combated by controlling OM buildup. And that the occurance of algea's get attributed to secondary factors. When proper and thorough maintence to control OM buildups can be the greatest tool. Also a healthy system non limiting in plant nutrients, will allow the plants to filter out the nutrients leached by OM's faster then it is available to algea.

Now I need an aspirin cuz that gave me a headache. I feel that the pieces are there but I'm just not grasping the total picture.

[plantbrain]

You may be correct.
I think staghorn, Compsopogon can be related to this and I've seen evidence it may appear due to this.

When I did progressive over loading of fish, I found it was common after green water. Not much thread, but that may be due to the GW effects on other green algae species.

Regards,
Tom Barr

[JDowns]

I should note also that my experience list for GSA was over a forty day period. I make 20 day stock solutions for NPK and allow the stock solution to run its course giving the plants time to adjust to the new routine. I just didn't want anyone to think that changes like this occur overnight.

[Robert Hudson]

One common source of DOC you forgot to mention Cecil in a planted tank is the plants themselves. Plants continually shed leaves that decay and build up if not removed and in a heavily planted tank, overcrowded with plants, the typical jungle tank can be a source of a major problem. "Leaf litter" turns into particulate and dissolved compounds fairly quickly and builds up a layer of silt throughout the tank. It not only affects water quality but the health of the substrate too. High levels of DOC create low levels of oxygen.