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Going from hitec to lowtech

V

vygec

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6 Dec 2011
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I started out my tank a couple of months ago, and i didnt realise exactly what i was doing, until i read up more and found this place!

Now the dilemma i have is, my tank is hi tech, sort of. Let me explain, its a juwel trigon350, low light running T8 lights with reflectors at 1WPG- 90w in total and the tank is 350litres. I run pressurised co2 and i have been dosing AquariumPlantfoodUK's All in One fert every other day.

The intention was always that this would have to be a low maintenance tank (with time constraints due to work/family commitments). I could probably get away with doing water changes every 2 weeks, but for this to be done every week, this was really going to make this very impractical for me. Now when i started, it was going ok with the fortnightly changes, but then i had a staghorn algae breakout, which i have just about bought under control- due to weekly water changes, after a few weeks).

Now, i need to reduce my maintenance schedule, so that i can change the water on a fortnightly basis. Is this possible somehow for me to achieve without having an algae problem again? what changes would be required?

I started a thread on my tank from before, so that can be checked for further details:
viewtopic.php?f=49&t=19633&p=199209#p199209
 
Anyone have any thoughts on how i can reduce my water change schedule please?
or have i completely messed up my maintenance routine :)
 
I've got such limited experience that I can't help much but what algae problems I've had were due to either: fluctuating CO2 (unlikely if you've got your pressurised system sorted); insuficient nutrients or not enough flow. If it were me I might try dosing the nutrients every day (but watch like a hawk for any worsening!) and/or increase flow. Actually, I think I'd go with flow first and try adusting that. I couldn't see above or in the link if you said you have anything but the standard juwel filtration, but what I can see is all in the back corner. This could mean that the flow isn't getting into all areas of the tank. So it might be worth getting a small powerhead and trying it in different positions to see if it helps.

Viv
 
Water changes are done in the following manner: Water is pumped out via a pump. I store new water in a water butt, dechlorinate, then pump into tank.

My co2 has been constantly the same since going pressurised (at least a month if not more). I forgot to mention, in addition to the juwel filtration i have an external eheim filter (which is rated for twice the size of my tank), i also have an additional powerhead on top of my diffuser to send out all the co2 and this also helps with the flow as well. initially i tried this in several positions, and then arrived at the current position.
 
Sorry, no help then :( Hopefully someone with more experience and knowledge will be along soon!

Viv
 
OK, so the idea is to reduce the water changes to fortnightly, instead of weekly. This is a tough proposition for a fuel injected tank, but the good news is that the lighting is T8 and not the high energy T5. In order to do this one has to understand the relationship between Light, CO2, Nutrients and Maintenance.

CO2 grows plants and when a plant grows it produces waste products such as carbohydrates, proteins, fats. Bits and pieces of the plant fall off and rot adding to the organic waste loading in the tank. So the the target is to reduce the growth rate. By lowering the CO2 and lowering the growth rate, the effect is that you also lower the requirement for nutrient dosing. Less CO2 and less nutrients means less organic waste production, less buildup of the waste and therefore less need to remove the waste as often.

The problem is that you cannot just reduce everything suddenly and get away with it. The plants have a specific requirement for CO2 which you yourself created when you added the level of CO2 that you have now, so like puppies, you will have to wean them off of the amount of CO2 being fed now. Unfortunately, while you're weaning, you still have to do the water changes. I'll just pick some arbitrary numbers there is no guarantee that they work:

Do a large trim/prune. This reduces the bioload and will reduce the demand for CO2/Nutrients while increasing the efficiency of flow/distribution.

Immediately Reduce the CO2 and nutrients by 25% - so if you are injecting 12 bubbles per second, reduce it to 8bps. Leave it for a few weeks. You might get minor staghorn and/or hair, so that's why you need to continue the water changes, and to clean and pick the algae off. This will be a preliminary response to the lowered CO2. In a few weeks this should abate as the plants become accustomed to the new lower CO2 level.

Do another light trim. Reduce by 25% of the new level, so go from 8bps to 6bps. Reduce the nutrient loading by 25%. Monitor for stress and maintain for a few weeks. Continue the weekly water change.

Another minor trim and another 25% reduction ought to get you close to your target, but wait a couple weeks before stretching out the water change - maybe go 10 days instead of 14 days at first. Monitor for stress.

Remember that large swords also have large root structures which add to the CO2 and nutrient demand. Optionally, the heavy rooted plants ought to be pulled occasionally and have their roots trimmed to keep the biomass low. Do this before you start to lower the CO2 and this lets them settle first so they are not extra stressed.

Again, the 25% is an arbtrary number. 30% might work, 25% might be too much so that 15% might work better for this tank. You will know the answer to this puzzle if you get large algal blooms. If you only get minor algae then you know it's OK, but you still need to scrub and clean it.

If there is any way to lower the light intensity/duration during this time it would help the transition and can be brought back up slowly later.

Cheers,
 
ceg: WOW :)
thanks for all your advice, you have gone above and beyond there for me, really appreciate the time and effort you put in.
i will begin to put this into practice and report back in a couple of weeks.
just out of interest though, since the last week i reduced my lighting from 8 to 6 hours. i have still got a bit of staghorn algae, no wear near as i did before, but this has been decreasing week by week..i had a thread on this too :)-
viewtopic.php?f=19&t=19967
 
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