Fertilizers and Water Changes

[maritzsa]

So I have a quick question. I have Seachem flourish and NilocG’s Thrive and I am testing both on different tanks. I am curious about water changes while using these products.

So if I have a 20 gallon and I use 2 pumps of Thrive (it says 1 pump per 10Gal) or Flourish do I need to do weekly water changes to get rid of excess nutrients or will my heavily planted setup be fine with a more scarce water change regimen such as once a month etc.
Is it better to guarantee that the fertilizers don’t build up? Or can I just keep dosing weekly without weekly waterchanges on a 20 gallon?
Also, when I do a %20 water change on a 20 gallon which is 4 gallons, do I dose the fertilizers for 4 gallons or dose for 20 gallons?

 

[Circus]

I would recommend doing weekly water changes, but that might be me being picky. I do about 60% (give or take 10%, depending on the tank) water changes every week, and dose for the full tank after the water change. No problems so far.

 

[Bruce Leyland-Jones]

I use Tropica's 'Premium Nutrition' to no apparent ill effect and probable good effect, (meaning I've had no 'melt' since planting in July and obvious plant growth).
I haven't lost a fish either.
I have just under 100l in the tank and 5 pumps per week are recommended. (1 pump per 20l per week).

I'm in the habit of changing 24l, twice a week, so called it 50l a week and decided to put 1 pump in with every other water change.

Math aside, it's basically what my old Organic Chemistry teacher used to call 'Bucket Chemistry', so precision isn't required and care is taken NOT to overdose the tank! Whilst an overdose (probably) wouldn't harm the plants, (though it may promote algae), I have fish welfare to take account of.

 

[xxBarneyxx]

I would (and have) just followed the instructions on the fert and do a 20-30% water change once a week on whatever day is furthest away from fert dosing.

You have no real way of testing what ferts you have in the tank, how much is being used etc. Removing ferts and running more lean by doing water changes is probably a better option then running heavy on ferts with no water changes. It may or may not limit plant growth a little but better that then algae blooms.

 

[Ch4rlie]

It is pretty much recommended by most that weekly water changes by at least 50% or twice weekly water changes at perhaps 30% or so is good fishkeeping practice.

This is for a number of reasons, one to reduce nitrate levels if plants do not consume this, second, to reduce any potential toxins and containments from the water column, third, to reduce the amount of debris and fish poop away from the water (can't be nice swimming around in water full of crud!) so fresh clean water is essential to the wellbeing of the tank inhabitants, and lastly to replenish minerals from tap water to the tank as plants and fish do need these minerals for their health.

What one has to remember, in the wild, fish are swimming in constant fresh water and what ammonia and nitrate being produced is a truly not a problem whatsoever due to the constant supply of fresh water. In aquariums, this is not so, so its a vast comparison, let us keep up the water changes for the livestock's wellbeing.

As for dosing ferts, well, this depends on what kind of plants you have, some will be root feeders and others will be leaf/water feeders, and also by how many plants you have in the tank as well.

Cryptocorynes and sword plants for example are heavy root feeders and they benefit greatly from root tab (Seachem Flourish root tabs are a good choice imho), while other plants such as java fern and anubias will benefit from liquid ferts to supplement nutrients in the water column.

I tended to use Tropica Premium for liquid ferts, dosing once a week just after water changes, usually two pumps for a 110 litre (30 US gals) well planted established tank. These plants in my tank were large and 2 pumps of this fert was just a supplement as my tap water at the time was hard and had high nitrate levels etc.

But of course fert amounts can depend on how large or small these plants are, young plants need a lesser dose while large established plants will require a larger dose.

By the way, I have never used NilocG products so I cannot comment at the moment if this is a good product or not or about the dosages required, would closely follow the instructions given on the bottle.

As @Bruce Leyland-Jones already mentioned, best to err on side of caution and not overdose the tank with liquid fertilisers as overdosing can cause a number of algae issues (algae uses the exact same nutrients as plants) and if there is too much nutrients in the water column for the plants then algae will start to use up some of the excess nutrients and then competition for the nutrients in the water starts to build up over time as the plants and algae grows.

 

[Byron]

I concur with the members who have put fish first, plants second. Fish are much more susceptible to water issues than plants, so assuming you have fish in the tank, they need the water changes but they do not need any plant fertilizers. Having said that, fertilizers are still OK but in moderation, not excess. Somewhat depends upon the fish species, but all freshwater species will be better off with fewer rather than excess additives.

As for the plants, as noted by others, this depends upon the number of plants, the species of plants, and the fish load from which plant nutrients can result. Fertilizers should be "supplements" in a tank with fish. I am not an aquarist who believes it is wise to harm fish or risk harming them just to have "x" species of plant which requires added substances that are not welcomed by the fish. Substrate tabs, at least the Flourish Tab ones, do not release nutrients into the upper water column (liquid fertilizers obviously do), so the impact on fish of the FT is right off the bat a non-entity.

I have floating plants in all my tanks because of their incredible benefits to fish and water quality. I also have zero GH/KH water, so no source of minerals. Relying on fish feeding alone allows my plants to struggle and frankly not really do what they are there to do (the benefits), so supplement nutrients in liquid form are frankly essential. I've been using Flourish Comprehensive Supplement for over ten years now, and I use as minimal a dose as possible (plant response guides this), once a week, on the day following the water change [conditioners that detoxify heavy metals as most do will negate these including iron, copper, zinc, manganese, so there seems little point in adding them only to have them being negated; 24 hours later is said to avoid this, so I've ben doing that].