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Discussion Starter #1
When running a tank in a borderline walstad method granted your nitrate consumption is keeping up with or exceeding the levels in your tank what else can build up to harmful levels if frequent water changes are not done? I know phosphatase in ratio to nitrate is very low so if nitrates are being consumed there should in theory be no free phosphates. I think I read there are something like 1ppm of phosphate to every 7 or 8 ppm of nitrate? My tanks are open top and evaporation is high so I am constantly replenishing with fresh water which maintains traces from the tap. I dose a full lineup of much needed Seachem ferts every week with my religious weekly water changes, I have tested before I do a water change and I am not throwing away any ferts they are all consumed within a week. I am thinking about dialing back my water changes and just dosing the ferts once a week along with top offs, the glass is always cleans via snails and the plants are always clean via shrimps. I would love to only have to do a water change when I vac the gravel rather than all these 20% water changes every week which is messy. I want to start more tanks if I can reduce the maintenance on my current tanks without negative side effects.

Would be great if I could reduce everything to once a month, filter pad change, gravel vac + water change all at the same time.
 

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Tom Barr has mentioned that plants in tanks without pressurized CO2 will grow about 6-10x slower. So basically, one can dose ferts at 6-10x the reduced dosage and do water changes only once every few months.

You make a good point about dosing micros in a tank that needs frequent top offs. I the same 5G tall, and was wondering about dosing macros but not micros. Tom Barr mentioned that one could test for Fe and use that as a gauge for all the other micros, but I don't have a test kit for that :(.
 

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I understand your point about reducing dosage by 6-10x however even before a water change after only a week nitrates are gone. This may not be the case with other nutrients but I have no way of testing Fe either to verify what is left in the water after a week.

I started a new maintenance plan, I switched from weekly to bi-weekly and I will see where this takes me! I am still dosing though on the off-week, I just reduced the water change to bi-weekly.
 

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I'd be eager to know how your new schedule works out!

Seachem makes an iron test that I might pick up. Maybe you can also look up reports for your tap water. I tried looking up stuff for my area and found some numbers for some things we care about, but not for others. Some things are also marked as "not detectable", but it'd be nice if they put a limit on what that means. It did list the copper in my tap water as 0.06ppm, kinda close to the 0.07ppm toxicity level that I found on some site for CRS and amanos. Maybe that's why I've only been able to spot 1 out of the 2 amanos I got :(.
 

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So I skipped my weekly water changes for a month, I went a total of 4 weeks with no negative side effects. The only thing it may have changed is my gH it is on the rise since I add a LOT of top off water to this open top aquarium. It went from 90ppm to 140ppm, I did a 20% water change and I still have to test the water to see if the gH dropped any. This seems to be the only thing I need to keep in check, along with TDS which should be taken care of by monitoring gH I hope...I do not actually have a TDS meter yet.

I have only one complaint over the last month and I am not even sure the lack of water changes is the factor. I am getting yellowing elder leaves and pinholes, my Java Fern is actually killing off some of its leaves entirely. This to me is a nitrate/potassium deficiency however some plants act up if your water gets too hard so I am not sure right now.

I carried out this experiment on TWO 5 gallon tanks I have, and I can say without a doubt it did not effect my nitrate readings on either tank. One stayed at almost 0ppm and the other never crept above 5ppm. I tested every week throughout the month and it never rose higher than 5ppm.

Conclusion is I will be dialing back my water changes to once a month, I literally vac my substrate maybe twice a year. Tanks are clean as a whistle too!
 

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I understand your point about reducing dosage by 6-10x however even before a water change after only a week nitrates are gone. This may not be the case with other nutrients but I have no way of testing Fe either to verify what is left in the water after a week.

I started a new maintenance plan, I switched from weekly to bi-weekly and I will see where this takes me! I am still dosing though on the off-week, I just reduced the water change to bi-weekly.


As with a lot of things in the aquarium hobby trial and error is sometimes the only method as each tank is different. I think your heading in the right direction changing to bi-weekly and see how it goes, if all goes well then taking the next step to 3 weeks and so on. Changing in small increments and seeing how far you can push things is about the only way to find your answer and I think your on the right track.


Dan
 

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Discussion Starter #9
As with a lot of things in the aquarium hobby trial and error is sometimes the only method as each tank is different. I think your heading in the right direction changing to bi-weekly and see how it goes, if all goes well then taking the next step to 3 weeks and so on. Changing in small increments and seeing how far you can push things is about the only way to find your answer and I think your on the right track.


Dan
I ended up stepping up to 4 weeks/monthly, all is good. However I need to increase my Seachem doses by 25% each week, my plant load seems to be more demanding. I am finding the older the tank it works its way into a walstad method with maturity.
 
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