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Best way to ramp down ferts in a low tech?


18 Apr 2012
Ok, part of my attack on the BBA in my tank is to stop doing monthly water changes (30%) and instead just operate on a "top up" basis.

To do that, I probably need to drop my dosing level. At present I'm doing 20ml for 190l every week of all-in-one ferts (James' recipe #3). Given that the dose is pretty high for a low tech tank, I have used the water changes to keep the TDS at something vaguely sensible (usually around 500/600).

What's the best way to go about reducing my fert load? In my mind there is probably an amount that's just pure excess across the board, but I bet some aspects of the fert are utilised by the plants since they've been available? If so, I'm guessing I'd have to very gradually reduce my fert dosing so that the plants have time to adapt?

Any pointers welcomed!

IMHO opinion, it would be better to name the thread: How to ramp up my water changes? Just because we can measure a few things and we have a filter, doesn't mean some other things accumulate and can cause trouble (read: death fish). For example, if the copper isn't used in the same amounts as the other traces, you might end up with a copper toxicity. Water is cheaper than fish, fish/plants love fresh water. One of the reasons are electrolytes, mineral cations. They get used and when you only add top up, you'll run out sooner or later. Off course this is theoretical but I don't want to use my fish as guinea pigs, and I think neither should you.
Hi Rick, nice to meet you. I am in no way a low tech expert, but I will tell you what has worked with my nano low tech.
Firstly though do you have the rest of your plans written down for us to see? It would help a non expert like me to envisage your new routine first.
What you have told me so far suggests that your algae problem is caused by CO2 deficiency, judging from the algae type. I would therefore suggest that if possible lowering your lighting levels would be a better option than stopping water changes. If this is not possible you could try adding liquid carbon to boost the plants' growth and reduce but not stop water changes.
I know this was not the help you asked for, and I am frustrated that I can't help more, but as someone finally getting on top of algae problems, I thought that it wouldn't hurt to share what little I know.
All the best from Bill
BBA is not something I've ever suffered in any of my low-energy tanks, in fact my tanks are conspicuously free of algae, except for a nice GSA patina on some rocks and on 1 or 2 old anubias leaves. But then I do a 50% water change every week, and my plants are never deficient in nutrients. I also use relatively low light intensity - which I'm sure balances low carbon availability and demand for nutrients - and I also use at least 10x turnover.

So if it were me I'd reduce my light intensity, work on providing good flow and distribution, and good tank husbandry - including frequent and substantial water changes to remove dissolved and solid organic compounds, and continue with the fertz. And combine the above with trimming and scraping the existing BBW in to extinction. Excel may help initially, to kill the symptoms, but is unlikely to cure the actual complaint, and if you're determined to maintain a low-energy tank it's kinda counter productive in the long term. You need to find the balance that hmm..."suits you sir", and provides a healthy tank.

Just in case you're wondering I don't subscribe to the whole water change - algae causing - fluctuating CO2 theory. I think that particular causal link - if it exists at all - has much more to do with exacerbating existing imbalance. But hey it's just a considered opinion.
Hi rick, have to agree with troi above water changes IMHO do more good than harm and I've had a few low techs run over the last couple of years not with soil substatre I will add but I have noticed a trend with my multiple tank setups, I have too many become busy at work and with life in general, the low techs go on the back burner then bba diatoms etc etc rears it's ugly head, I then become more diligent clean substrate, filters,change water etc etc and remove the algae manually and it doesn't come back until I have a relapse due to work life kids etc etc, not scientific I know but as I said its a pattern water changes has halted.
Thanks for all the replies guys. The whole reason I go low tech is to avoid maintenance, since I don't really have the time to commit on a regular basis. My thinking around the water changes was that in a few BBA threads on here the suggestion has been that water changes often lead to a CO2 swing and thus BBA outbreaks.

@Troi - Thanks for that, I'm thinking that even though my flow "appears" to be ok (minor movement throughout the tank), maybe I should get my hands on a Koralia or similar and have a rethink. That said, I realise that too much flow will be just as negative as too little, so who knows! The odd bit I can understand being flow related since I have anubias nestled in cracks and so on, so poor flow over those small areas isn't surprising in isolation.

I'm keen to use the LC to remove the BBA not to fix the problem, but more to remove it so that I can see if it returns, or if I've fixed the root cause. That said, my last spot doses with 1.5% homemade LC have been ineffectual, so I suspect I might need to make a fresh batch (and I'll make it 3% this time).

Thanks for all the considered opinions guys!
No worries, maybe it'd be an idea to go with the relatively high maintenance regime and LC until you've conquered BBA, and then ease off and find a lower maintenance equilibrium that you're happy with...which I'm almost certain will involve less light - intensity/duration - maybe then flow won't be an issue either (if indeed it is). Don't worry about large frequent water changes and the CO2 thing, in your case it's a good bet it'll be far more beneficial than not.
Thanks for all the replies guys. The whole reason I go low tech is to avoid maintenance, since I don't really have the time to commit on a regular basis. My thinking around the water changes was that in a few BBA threads on here the suggestion has been that water changes often lead to a CO2 swing and thus BBA outbreaks.

While doing large water changes, plants get exposed to the air and have all CO2 available they want. They suck up for the rest of the day and you can in theory leave the CO2 off for that day even in high light tanks. You won't be able to top the concentration of CO2 they inhaled during the water change. This is off course only true if you do large water changed where all plants get exposed to air. You can run very high light by just draining the tank each morning and putting (the same) water back in. I've seen people do this with very small nano tanks and it works a charm!