DPatel304

Newbie: Please help me finalize what I need to buy for my 75 gallon system

9 posts in this topic

I have a 75 gallon fish tank, and want to create an indoor system.  Here are the list of parts I have so far:

 

I mainly want to confirm that the fish tank pump, siphon type, and grow bed are all good.  From what I understand, I need to cycle the entire tank every hour, so I could run this pump for ~12 minutes every hour to accomplish this.  The grow bed is small, but perhaps I could have 3 of them.  I'm not quite sure what my ratio of grow bed to fish tank should be, I've heard 1:1, but that sounds like a lot.  I'm not sure I have the space for more than 3 of the containers I listed.

 

Any other tips/suggestions would be very helpful.  As far as fish/plants are concerned, I'm looking for the easiest.

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from my understanding by what i have read, 1:1 ratio concern mainly for healthy plant growth, but if your grow bed is too small then you may need to add a filter for the solid fish waste since most people that uses media grow bed mainly uses it also for bio filter. just don't over feed your fish as that will produce way too much ammonia and nitrites which will kill your fish. i don't think having more fish can be bad, but having way too much plants may be bad for your plants if your fish + bio filter cant keep up with waste to No3 conversion.
i am now waiting also for my plant to grow, but doesn't seem to be so healthy, check it out maybe you can give me advice.

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Thanks for the response.  So, in addition to my 400GPH pump, I want to add a filter to the system?  I'm not sure how to properly filter the right amount, yet also make sure the plants are still properly fed.

I'd prefer to use the grow bed as a bio filter, but if that's not an option, I'm open to modifying the system.  Is it possible to get 'heavy feeder' plants that might require more intake and balance the system better despite my grow bed being small?

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Posted (edited)

Your pump is 400 liter per hour and your fish tank hold 300 liter, in my opinion if you have grow bed that hold 100 liter it is enough, since you cant posibbly drain all your fish tank water to fill your media grow bed. If you go 1:1, im quite sure your fish tank wont have enough water since for it to fill the media grow bed and drain back. 

im currently testing a DWC system, it now has almost 400 liter of water. If i feed them too much the water will be cloudy, that is 3 times a day for four day straight. But if i feed them 2 or once per day and alternate with duck weed, the water stays clear with the addition of a bio filter of course. So if you flow your solid fish waste directly into your grow bed, i dont think the filteration will be enough to keep the water clean and to keep the solid waste staying at the bottom and not sticking to your plant roots. I think you need to pay close  attention to your feeding intensity if you are going to have no extra filtration and only a 100 media grow bed that act as a bio filtration. I have read adding worms actually help break down the solid fish waste on the grow bed, maybe you can add those if you dont want to have extra filtration.

if you turn your pump for only 12 min per hour, how are you going to achieve 300 liter per hour water exchange? I have read quite a few people saying that the water exchange should happen at least two or three times per hour.

even if you add heavy feeder plants, i dont think its going to help, as plant consume nitrate, whilst fish waste being ammonia and solid waste needs to be broken down and converted to nitrite and then nitrate - what the plant needs is the No3. Fyi, the filter doesnt filter out the nutrition for the plant, but keep the bad things and turns it to good things for both your plants and your fish. You wouldnt want the fish waste to flow back to your fish tank. Normally the flow will be like from fish tank to filter then to the grow bed after this, back to the fish tank.

but with all that i said, im not an expert im also trying it out for the first time. I dont know where the expert has gone to, since no one is replying my thread also.

Edited by Moses (see edit history)

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Hi DPatel, Hi Moses,

I am always hesitant to offer my thoughts about small indoor setup 'ideas'.
Although the inherent principles are the same to larger outdoor systems, the requirements and maintenance is much higher.
The 'successful' small setups ive seen are all using high tech gear to attain a balanced system that produces product.

None the less, I'll try to address your questions;

Filtration
10 gold fish in 300 litres will produce a heap of waste.
No filter = higher grow bed maintenance/issues = higher failure rates
As the waste builds up and then breaks down in the g/b media the resultant bio sludge creates anaerobic pockets, restricts even water flow through the media and generally plays havoc with water chemistry over time.
I would consider a pump with a built in filter, something like this one perhaps. Easy to clean regularly, keep that waste out of the g/b.

Flow Rates
Once per hour is a recommended minimum, dependent on tank volume and fish biomass, refer to my 10 goldfish comment above.

Bell Siphon
That looks like a solid unit.
Often can be cheaper to make one from pieces from a hardware store, but hey, getting all of the cuts/depths/lengths correct can be a chore.
The actual functional performance of all bell siphons is a variable of water flow rate & grow bed dimensions.

Grow Bed
Again, that one looks like a reasonable food grade item.

Media
Hydroton is popular and works well.
However, being a porous media is subject to bio sludge saturation, without some sort of prefilter of solid wastes.

Grow Bed Ratio
This is another variable, dependent on the above factors, and others.
As mentioned by Moses, this proposed design will potentially drain up to 1/3 of the tank before the siphon kicks in.
Then you have the pressure of 100ltrs falling into a glass tank rather quickly... (I assume is it glass as you have not stated otherwise) ...

The last item in the highest requirement... Grow Light.
2 simple words = the highest tech item to grow food/plants.
There are grow lights, and then there are Grow Lights.
Ive not looked into specific units for a long time.
Each plant has its best light spectrum requirements, otherwise photosynthesis is hampered.
Light Intensity is next. Do some google searches and see how many lights (lumens) are used (needed) per square foot in 'successful' systems.

Some things you have not mentioned;
Water Test Kits = Get some and Use Them, regularly ! (if you dont have already)
Supplemental Aeration = Not always needed, but I do recommend, especially with systems on pump timers /or pumps off at night etc.

Hope this has shed some light on your thought process.

Cheers
Joe

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Looking at your list I would make sure that the grow volume  can accommodate your pump, and vice versa, with this pump you need more volume, 1:1 is good, on paper, but a 2:1 ratio is easier to live with, the higher the gro vol the safer,  use your present grow container for the filter and get a 50 gal tote. About $20 at Walmart, or comparable.  Life will get a lot better. On your lights, check out the wattage for every type, thats what you are comparing .Thats what you need to compare between types, how much wattage are you getting per dollar.  Thats my 2 cents. My favorite filter is a large  container under light, chock full of floating plants like hornwort, or other fast grower, several big public aquariums use these for both fresh water and marine systems. In the marine of course with marine plants. Another name for this is a refugium. I love them. I consider it the fool proof system, with me as the fool.

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Hi Jake,

A larger grow bed will empty his fish tank during the flood cycle.

Wattage has little to do with indoor lighting.
The essential criteria are Spectrum & Intensity.

You can replace a 1000w high pressure sodium light with a quality 300w led light and still get the same intensity BUT with a more accurate required spectrums AND with a HUGE saving on power to run it.

Cheers
Joe

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That is why you have the pump on a timer. Dr McMurtry discusses this.  He uses/suggests a 15 min flood cycle.  He also stresses the use of sand in 'his'  IAV system. All of his results and writings are on the use of sand, right down to the size of the sand.

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To further this on the pump and grow bed, Dr McMurtry suggests a 15 min pumping time per hour for the flooding stage, and then an hour to drain. This needs a careful choice on the pump, that is capable in 15 mins to give a 'flooding' to the bed, another reason why he is adamant on using sand for the growing bed. So if your goal is other then a McMurtry IAV bed then your choices are your choices, some will work better then others. You didnt mention the size of your goldfish whether they are little guys or adult near spawning size. So there is a lot of room for you in your system to tweak it as you want, your results can vary, but its all up to you, a lot of different configurations can work very well for you.

I have parts for a similar system for myself, inside, and almost at the same time acculating material for a flood and drain in a hoop house next to the house. FWIW, the inside one will have 2Xs the gallons in the grow bed, as the tank, and it will also have a 50-75 gallon sump/reservoir , the pump will have capacity to flood the grow bed sand in 15 mins, and then it drains. I will tweak the flooding time to what seems to work best, I expect  every other hour. we'll see. The inside tank is 75 gallons, and it will have 15 koi,  about 5-6 " to start. The hoop house will have Blue Gills. To start, maybe a 2nd system with Yellow Perch.  Right now emphasis is on putting the inside system together.  The hoop house will probably go together after Labor Day.  So , we shall see, most of the inside parts, the main thing is to build the grow bed. It is taking 2nd place to another outside project, but it will come together.

 

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